I like the economy, and there really is plenty of exploration unless you've played earlier X games as a good deal of the sectors are pretty much the same.
Anyways, I picked up X3TC last January/Dec IIRC but never really played for any length until recently. It seems to be the easiest X game to date, although I'm abusing the hell out of Nividium mining in Queen's End ATM IIRC.
Played it alot for a while then bought Evochron Legends when gamersgate had a good sale. EL is getting better, but it's not up to X series or Universal Combat yet. Some nice new features added:
being able to own multiple ships, but you have to store them, up to 5 IIRC excepting the one that you're actually using ATM. Some crafting. MUCH improved graphics. WEAK quest. So-so combat(better than X, but not as good as UC). BEST online MP. Economy/trading sucks, worse than UC's gimped trading.
Still ends up boring as ——all in the end though. Maybe the next one will hit the magic combo button.
JDR13 you might like this game as there are some hidden areas/systems to find, and he apparently included the Solar system which is DIFFICULT to get to. Might want to wait for another sale though.
Anyways got tired of EL, didn't go back to X3TC ATM, need to practice combat in X3TC. (Actually have X3R and X2 installed as well…) So, I re-installed Demise: Rise of the Ku'Tan and have been playing that this week. (E-mailed Decklin about 1.03 Pharoah Production upgrade(I have the original Artifact Entertainment CD release), and found 1.03 doesn't work on Vista but he said to wait for Ascension which should be out later this year at a pretty good deal… He hasn't posted publicly AFAICT what was in the email so that's about all I'll say ATM.)
[EDIT]
Now that I'm thinking of it, I was already doing pretty well in combat so I was actually at the point of deciding what stations to blow my billions on before it overflowed the magic c. 2.4B credit number... (You can get around this by dumping extra cash on stations, it's just you as the character that are limited to a signed(WTF?!) 32b number max "on your character".) Need to find a nice safe sector to destroy the economy in since I'm not high enough ranked(fighting) to buy the really nice cap ships(Terran) that I want... up to a station transport and 2 M6s plus misc. capped M3s, M4s, and M5s. OH, and a small carrier, military transport IIRC and 8 or so sector traders and 3 Universe Traders.
Don't feel like tackling a complex yet though...
[/EDIT]
Darkstar One: I picked up that one in a sale, found it easy and well, meh overall. Combat was fairly easy, trading boring, storyline boring, but the graphics were nice but not enough to keep me playing it and leaving it installed.