I would recommend a Cruiser or a Science ship the most. A Cruiser has the tank to survive but adding in your Tactical skill can make it actually deadly and maneuverable. Also you can get much more mileage out of Go Down Fighting which is a POWERFUL ability when stacked with Attack Pattern Alpha. The more hull damage you have the more GDF will boost your damage but in weaker ships you cannot afford to leave your hull weak for more than a few seconds or you go POP. Fire on my Mark makes your weaker beams actually deadly.
A Science ship can disable enemies viciously and leave them defenseless in mere moments. When that happens popping an Attack Pattern Alpha and laying in with all you can will often lead to a ship popping real fast. Science ships can also take advantage of GDF but not as well as Cruisers unless it is the D'kyr which is one tough ship. Fire on my Mark can make your lower number of weapons irrelevant.
I would recommend AGAINST Escorts... I know that sounds contrary but consider it for a moment. Escorts have the Tactical BOFFs to take care of all their Tactical skill needs. Attack Pattern Alpha may be better than Attack Pattern Omega III but is it not simply redundant? What Escorts need is some way to mitigate their Glass Cannon Status. They deal vicious withering damage without any help. Science officers provide them some resistance buffing, Sub Nuke to clear away all those annoying buffs your enemy has, and Photonic Fleet is a nice distraction for an Escort pilot. Engineers can really help to keep a Balsa Wood Escort together even in dire straights and their EPS Power Transfer and Nadion Inversion can keep their big bulky cannons firing strong even under the most vicious of volleys.
So there you have my recommendations. Take them or leave them as you will but I have been known to be very good at analyzing this sort of thing.
Personally I will sort of go with what has been said before in that science ships for a tac are nice, as they give a compromise between maneuverability and toughness. It is only when I go into the STF's that I switch to a full on Escort for the firepower that only cannons can provide.
The damage output of an Alpha strike from a Tac in an Escort running cannons and turrets is second to none.
It can drop virtually any non-STF NPC in 1-2 seconds flat.
Though an Alpha Strike from any competent Tactical Officer in any properly built ship can do the same...
The only difference is that a Tactical Officer in an Escort cannot hope to take any return punishment so if their target survives their best attack (Sci Captains can pull that off real easy) they can be seriously up a creek.
Well, My main toon is a Tac, and I would recommend whatever ship you like best. I personally fly the defiant-r, and there are few players in this game that can stand up against my alpha strike, and my sustained DPS. I have also learned to tank fairly well in it. I have tanked other SCI ships, (Without Science team), and against cruisers.
I have even tanked other escorts. If you are absolutely against escorts, then I would vote for a sci ship. I put my eng in the intrepid, and he has great sustained DPS. Those are my thoughts. Hope it helps