I suggest Star Trek Legacy as the in the last few years there’s only been a few trek games. The games out there are Star Trek Legacy, Conquest & Encounters which are all basically meant to offer the same space strategy of the last 40 years of trek. They have different gaming experience as they're tailored for the system they were released on.
If you've got a powerful PC then I would strongly advise you to get the PC version of Legacy as thanks to game mods there are now changes to the game that allow for something as basic as a level select or ingame saves or a full mod like the Ultimate Universe Mod which adds a LOT of new ships & basic stuff that are in the game, but were never made available for unknown reasons.
As for the X-Box version I know it's still well played online & it is a great game. The only hates I have is you can't select a era or mission to play & if playing on a standard-def screen then expect to breifly see damage textures randomly appearing on your ships hull.