the one game ive seen that really did privateers feel for me, and nicely put a "getting out of the spacecraft and wandering about" edge on things was Earth and Beyond, sadly with its closure, no more will i bound from planet to planet and from station to station trying to find the parts to build myself a 200% x3 missile launcher - seriously though, that game had some real quality in it, and i was lucky enough in my summer of playing it last year to get some of the really killer battles to take part in
to be honest though, marine/space combat cant mix in the WC world, you cant really fly into a carrier with marines and hop out and kill everyone, because youre a pilot unless you were some special combat unit it just wouldnt work. however, if the game were worked like "Space Above and Beyond" it would work really well.
as for other space games, i tend to collect most. tachyon is ok, but its not superb, the combat is nice though, and definitely the AI roasts some of the older WC AI (perhaps even prophecy's) X and X-BTF were tough ones to call, managing in the 2 of them to be linear and open ended, and to generally be a bit wierd, they were worth it though. on the other hand, theres few games ive anticipated as eagerly as X2 and i can safely say it was worth it, a little suspicious here and there, but when i got the UK version (which comes pre-patched) it was so much more stable and much much happier running on my pc. the game does take forever, after a few weeks id managed to get a power station, a couple of transport ships, and id managed about 3 missions on the storyline. the true beauty of the game is in that, working to make an empire of industry - just what the privateer doctor ordered!
independence war's demo is all i ever managed to play, but i can say that one was fun, the sequel i havent gotten around to finishing yet (or really playing) but the demo of that was good too.
on a slight sideline, starlancer was excellent but the last mission always crashed out for me, faulty cd or whatever ive never seen the last cutscene, it dies either when i see the admiral and his cutscene or when i see the last boss' fighter. (and it dies with and without no-cd cracks)
ive always wanted to play archimedean dynasty because i heard good things about that back in the day, but sadly i never got a chance, however the aqua nox games - which are archimedean's children - are both good, and whilst very linear (not quite sub-culture, which i loved the randomness of) - are very fun.
finally team17 (maker of worms) did a space game a year or 2 back called phoenix, which is short but sweet and worth looking into.
that said though, dont let the CIC's aged members fool you, theres som really nice looking games coming out in the next couple of years (see fileplanets movie collections, one of them is a space marine type game as discussed) and whilst the space game market seems relatively slow, it by no means seems unwilling to spend on at least one beautiful work a year