never played JK2 multiplayer, singleplayer was good, though I've noticed a few things that were pretty stupid (like Desann's lambda shuttle's cockpit not having glass and being smaller than Desann and Tavion). JK3's multiplayer had a lot of glitching for me + the lag and stuff...singleplayer story could have been much much more...also, I've never understood jedif (the jan with a double-bladed lightsaber), what is up with that?
but if you want atmosphere and ambience, play KOTOR 2! it was rushed, sure, but it's still a great game! (especially with all the restoration mods out there)