Probably Definitely Maybe or Morning Glory. If we're talking about Oasis with Gem/Andy, then my favorite is Standing on the Shoulder of Giants. ^^ I like DBTT a lot too, my favorites are Turn Up the Sun, Mucky Fingers, and The Importance of Being Idle.
Definitely Maybe is good from start to finish. Out of all the songs, I really love Shakermaker and Digsy's Dinner, both being pretty quirky tunes haha. Have you seen Familiar To Millions?
Ah yeah those are good ones too. ^^ Noel did an acoustic version of Slide Away live, it was pretty great! I think I liked it more than the original. Familiar to Millions is good. It's from 2000 and Liam is at his best imo. Best meaning funniest, his voice is kinda eh. But not as eh as it is now. :S
Haha I'm not Liam's biggest fan tbh because I think he's a douche but I love Noel, he's hilarious. Saying that, Liam when young was gorgeous and I will always love his voice.