FSA are the beginners force of choice - they are apparently the best all rounders with the best starter box.
The Brits are pretty good, I play KOB and Covenant and although I much prefer the Covenant ships the Brits can be fairly hard to beat. They have some excellent torpedo capability which doesn't get reduced by damage. The battleship doesn't dish out the most damage but you give it 2 shield generators and it will take your opponent all night to sink it!! The double shields make it hard as nails, just steam it into the midst of your opponents fleet and let rip.
And.. the energy turrets are proving to be better than expected. A few games in with them now and I think I'm getting there. Using them is forcing me to adopt a very specific style of play but its been fairly effective so far.