Thats three massively different types of game.
BFG is a great game and I am a massive fan. Its simple, cinematic, interesting... and dead. If you can get the minis, and you generally like GW rules philosophy, its certainly worth looking into. For me, it hits a nice balance between a fun relaxing game, and tactical play.
Full Thrust is a little more complex and a little more 'realistic' (whatever that means). It deal with inertia better and is more in depth. It takes a few games to get into, and I guarantee that the first game you play both fleets with power right past each and have to apply a handbrake turn quickly.
Firestorm is a more abstract game than the other two, dealing with range bands, fistfuls of dice and 'exploding dice' on 6's. I havent played this one, but its essentially Uncharted Seas in space as far as I can tell (not that this is a bad thing, since BFG is basically Napoleonics in space).
Other potential games are:
- X-Wing (the Miniatures Game, which has a good following, or the Star Trek port of it)
- Starfleet Captain
- Hostile Stars (sneaking that one in there)
- Dropfleet Commander (when it hits release is you can wait)
- SITS (Saganami Island Tactical Simulator.... if you like your games with a slide rule)
- Starmada (does anyone play this any more?)
EDIT - BFG additional material is here:
-
http://www.specialist-arms.com/bfg/warprift/-
http://www.specialist-arms.com/fanatic/
_________________
https://www.cybershadow.ninja - A brief look into my twisted world, including wargames and beyond.
https://www.net-armageddon.org - The official NetEA (Epic Armageddon) site and resource.