I've played both X2 and X3. Honestly, X3 is an improved version of X2. Practically everything about it is better - menus/UIs are more fluid, you can actually play with a mouse, combat is better, the engine is prettier/runs better, etc. I played X2 A LOT (at least 100 hours, probably more) and only got an M6 (frigate, biggest "personal" ship), a TL (huge transport ship), some fighters, and a few factories. There are tons of guides on the games - playing it really feels like a career.
They're truly great games, but be prepared to spend a lot of time to learn the game and to get anywhere. Oh, and the story lines kind of suck. Seriously, the "Khaak"?