ABlackMan
Superstar
Madlib calls himself the Loop Digga for a reason. That's part of his style to find rare and obscure loops or just use loops period. He also chops as well as anyone but loops are his preference.
He can blend different chops together:
Alchemist doesn't really chop like he used to. He's more loop based now.
The reason I say Madlib is better than Al is he's way more diverse in his sounds. He can do jazz, soul, dark, grimy, melodic, etc. You don't see Al branching out like that. It's a lot of sparse sounds, Eastern European jazz, dark piano loops, and some soul thrown in. Madlib is just more musical and unpredictable and that's why his work is more interesting to me. You never know what a Madlib beat will sound like. You'll get Thuggin or One Beer.
Listen to Madvillainy, Pinata, and Bandana and hear how many sounds and styles he goes through. The albums Al does don't give you different vibes like that. I don't think Al has an album that touches Madvillainy. His albums with Gibbs are better than Alfredo. Still love his work but listening to an album like The Elephant Man's Bones I got what I expected. He gave Benny beats that I expected. I never know what to expect from Madlib because his sample bag is so random and the artist has adjust to something different.
Even with Madlib being a hermit and rarely releasing music I think his work is superior to Al.
Go listen to alchemist solo albums he put out recently