Its really up to you. There is many decent loadout option.
1xDual Phaser array (because i have beam overload I); im still looking for normal phaser array MK IV with crit, need couple of more badges
1xPhoton tube with crit preferably (because i have HYIT I)
1xDual Cannos/Dual heavy cannons (because i have rapid fire I)
1x Phaser turret
But thats my setup :-) some people skip the beams and go for cannons only..i like the extra punch of beam overload
This was because I found this really god cannons with a very wide angle of attack so I could unload both phasers and the cannons on my enemys while circeling them.
If you like to do "strafing runs" more, then you may want to replace the rear phasers with a turret, it wont do as much damage but it will be able to fire forward, so it balances out.
Also, one player I did a few missions with swore by ALL forward facing cannons and a mine launcher in the rear. You would be able to do very high "burst" damage but against enemy battleships it would take forever to kill them without torpedos.
Edit: Looks like Dalnar beat me to it! But I forgot to mention this was on the Federation side, my Klingon Bird of Prey was a whole different animal.
this setup allows 3 forward attacking high DPS energy weapons + a torp launcher. If you are willing to do the work to keep facing your target it makes you a dmg power house. Nothing survives your first pass if done right.
Just dont be afraid of changing weapons and testing what may work for you best. I personaly like forward beam because it allows me to do one overcharge beam while i fly past that target...but thats me, because i rarely just park my escort and nuke..i fly alot, thus i like all options available me. And also, you should consider if you will mostly pvp and pve...both will require a bit different aproach, both in loadout, and BOs.