really depends on what you like to fly...most dmg you will get out of an escort. and there you got the most damaging with 5 tactical slots, but also some other more versatile ones.
so, there is no "best" ship for a tactical captain...there is only a best ship for you and your way of playing and that you have to find out by yourself.
i do not mean buy them all and test them, just ask yourself what you want to do, what kind of ships you like, etc.
if you are more the heavy guy...with thick armor, but still potentially good dps...then a tac cruiser like the tac oddy is ok for you.
if you are more the rogue style player, that is looking for the high dmg numbers, but accepts being a little squishy in return, then an escort is the proper choice.
Even sci vessels can work in combination with tac captains.