At least someone hasn't answered your question with a completely different ship that you didn't ask about. I give this thread three or four more posts before someone tells you to fly an excelsior instead.
Don't pick up the Odyssey because of the Aquarius. Although some disagree - I am guessing those that do are max spec'd for threat or something - the Aquarius is essentially a flying coffin.
IMO, for general use the tac Odyssey is by far the best of the three C-Store Odyssey hulls (sensor analysis in my experience is nowhere near as useful as others think it is, and in one PvP situation probably cost me the fight), but the Aquarius is the worst of the "extras." I'd say that the Odyssey mostly shines when it has the saucer sep available to it, and perhaps with the three-piece set. I use the set when I use my Odyssey.
But redoing my tactical toon I find myself preferring my Regent. In fact, I recently picked up the Fleet Assault Cruiser, so I likely will not be returning to the Odyssey on that toon in the foreseeable future. While it may be technically the "inferior" ship, with less hull, lower shields and one fewer console, the console is usually lost to a gimmick console, the endurance comes at the expense of maneuverability (that small amount of it can make all the difference in the world in KASE in my experience), and the wide-arc quantum torpedo adds an invaluable torpedo boost to broadside maneuvers. Also, in Elite STFs, random deaths happen often enough that separating the saucer can be a risk - get one-hit killed or have your shields stripped off at the one moment, and you're beaten and lose the saucer separation for 4-5 minutes, depending on if you have the whole set or not. The main "sticking point" I can see is that the Odyssey can be configured to be somewhat more tactical than the Regent, although if you are willing to give up science (and hopefully have someone to help you with Hazard Emitters) you can match that level of tactical BOff power with the Regent as well.
That said, I agree with the previous poster who said that you should consider what role you want to play. The Odyssey is certainly more versatile, and in its non-fleet versions the Regent is nowhere near the same tank-wise. However, the Assault Cruiser series seems to have certain levels of balance that other ships seem to lack, hence why they are favorites; that said, the Odysseys are popular due to tremendous versatility (and other reasons), so they are not to be discounted, either. I would have to say that the Regent is better at being a DPS-oriented tactical cruiser, whereas the Odyssey tilts more on the tankiness side of the equation with more room for versatility, especially with the three-pack, and if you have the saucer separation you have a high-maneuverability 'intense DPS' mode available.
Ok so I'm torn between these two vessels, I am leaning towards Odyssey cuz of the Aquarius escort and what not and cuz you know, it's the biggest starfleet ship yadaydayada.
Only problem is every bob and is dog has an Odyssey and I rarely ever see a Regent flying around...
Did I just answer me own question?
Do not get the Tactical Odyssey just for its Aquarius auxiliary craft. The Aquarius will flit about a little, maybe deal a couple thousand damage, and then die as soon as anything brings their guns to bear on it or explodes near it (and since pet AI is kinda terrible, those two things tend to happen more frequently than most people would like). The Chevron Separation console from the Ops Ody is better due to it improving the mobility of the sluggish Odyssey when separated, but the Chevron itself is similarly usefulness-impaired.
Instead, get it for the frame. It's a tough ship with a decent console arrangement and both a Lt Commander and Ensign Universal officer slots.
On the other hand, the Regent is slightly more agile and has a slightly different layout when compared to an Odyssey fitted with a LtC Tactical officer, one favoring Engineering slightly for what could be considered a slightly more balanced approach. In addition, it carries the Wide-Angle Quantum Torpedo, a valuable tool for improving your broadside without further draining your weapons power. The Metreon Gas Container console and its associated Riker Maneuver power are about as hit-or-miss as the Aquarius tends to be.
Love my Odyssey, but the Aquarius is really just a toy and not a very good one. The Tac Oddy's big advantages over its Sci and Ops bretheren are the extra tac console and the +10 weapon energy, but those advantages are abilities the Regent also has. Ultimately what it comes down to is that if you get the Odyssey Tac, you'll get an account-wide ship with a 1.15 shield modifier, 2 universal boff slots, and 10 console slots standard. If you get the Regent, you'll get better turning and the wide-angle torpedo (the fart-bomb console is more a gimmick than a genuine tool), and while you can upgrade to a fleet version with a 1.1 shield and 10 consoles (including 4 tac consoles), that'll cost extra and you'll have to find a T5 shipyard to do it. Generally, for toughness and versatility and still a decent punch, the Odyssey is a better tool. For maximum emphasis on offense, the Regent is superior.
The Regent is a very offense cruiser, and it has a universal boff slot, but the tactical odyssey has 2 universal slots, and it's a little tanky... but here are my thoughts
If you want a torpedo launcher that helps you vroadside with THY III, Get the Regent.
I am absolutely in love with mine and I even picked up the Fleet Regent. Granted I replaced the Metreon Gas Canisters with Theta Radiation Vents, but I absolutely love the Wide Angle Torpedo Launcher.
The Odyssey? Doesn't have the amount of Tactical consoles unlike the Regent, and you have to use the Lt Cmndr uni slot for Torp High Yield III
Yes you get a shield modifier of 1.15 with the Tac Odyssey, but if you really want to dish the pain, I highly sugget the Regent, then the Fleet Regent at a Tier V shipyard.
The Regent and Tac Oddy are two very different ships. I'll go over them (since I own both) and tell what they are good for, and what they aren't good for.
Starting off with the Regent, this ship is basically an upgraded Sovereign. It has a decent Tactical layout for it's BOffs, but has no starting science BOff. This can be compensated for by making your Universal Lieutenant slot be science. It has a 3/4/2 console layout, skewed in the direction of tactical and engineering. It has decent hull strength, decent turn rate, and decent inertia. Overall, she's a strong choice. Simple, easy to understand, moderately easy to use.
The Tactical Odyssey on the other hand... well, she's an Odyssey. She has wonderful hull strength, a great shield mod, and a very balanced 3/4/3 layout, skewed towards engineering, but equal in science and tactical. Adding on to that, her BOff layout is very very versatile, with the Universal LtCmdr and Universal Ensign. Her starting BOff slots are Lieutenant Tactical and Science, with a Commander Engineering. So with her universal slots, you can give her a LtCmdr Tactical, and you have that Ensign to strengthen another area on her. But that's where her positives end. She suffers from the same problem all Odyssey class ships do. Her turn rate is terrible, as is her inertia rating. By herself, the Tactical Odyssey is not a great ship. She has the potential, but by herself... not so much.
However... if you get the Odyssey 3-pack, all of a sudden, the Odyssey becomes VASTLY superior to the Regent. Reason being? Two words: Chevron Separation. This console comes with the Operations Odyssey, and it basically takes your Odyssey, separates your saucer which hits your hull and shields a little, reduces your power levels slightly (-10 to shields and aux... which does hurt a little), but in return, gives you 10% impulse power (can fly faster), an additional +10 to your weapons power setting (very important, especially for beam boats), and increases your base turn by 8. It also gives you a non-controllable pet that has two mk X white phaser BAs, a tractor beam, and an ET1, which it uses on itself and occasionally you. Basically, you become quite nimble, and have stronger teeth, with a little buddy following you around. This alone makes her stronger than the Regent. But as I stated, you need another of the Odysseys to do it, and by herself, the Tactical Odyssey really isn't that great.
The Aquarius Escort Console is frankly quite useless. The Aquarius will launch, do some great damage for a little bit, then fly too close to a warp core breach and die. Yeeeeah... not really that impressive. The Saucer from Chevron Sep has the tendency to do the same, but even if it dies, you can still fly around without it and keep your bonuses.
Like the Aquarius console, the Chevron sep has a 5 minute cooldown, so if you die, you will lose all the advantages you had with it for 5 minutes. Also is prone to randomly bugging...