They're substantially different games, so they're tough to compare without knowing what kinda game you like, ya know?
Rebelstrike's less thought and more action... KOTOR is a larger game overall, with a deeper storyline and more thought than action.
one's an RPG, the other's an arcade-style flight shooter.
KOTOR is set way before even the prequals, Rebel Strike is set during the Galactic Civil War (From the Battle of Yavin to Battle of Endor).
Neither's perfect, but neither's being given a negative review either too...
So it boils down more to if you like an RPG game, which KOTOR is, or if you like a flight/shooter game, which Rebelstrike is.
I'm not the owner of KOTOR as I don't own an X-Box, but it's coming to PC which I'll buy it then anyway... Rebelstrike I'm buying HOPEFULLY this week. Maybe tomorrow night, as it's in the store, but my free time to go over is limited.