Going purely by success it's T.I. of course but in terms of quality music for me personally it's...
1. Jeezy 2. T.I. 3. Future 4. Gucci
I can honestly say I've bumped every project Jeezy has dropped (except Church in the Streets). We ain't even gotta talk about TM101, 102, or The Recession. Jeezy got classic mixtapes most cats best albums can't even fukk with (Trap or Die, Can't Ban the Snowman, Trappin Ain't Dead, It's Tha World 2, etc.)
T.I.'s great music run started with Trap Muzik and ended with Paper Trail. Everything after that has been weak and gotten the skim treatment.
DS2 is the only Future project I've bumped front to end. The rest of his catalougue, I just pick and choose songs. One could argue that Future has the best collection of hits/single songs of the group. For a quick listen, I'd take Future over the others .
Outside of the State vs Radric Davis and the rare mixtape joint, I've never bumped Gucci like that even during his "run". Gucci is probably the realest of the group (Jeezy and T.I. both fraudulent as hell) but the discussion is quality music.