@Klypse
Jazzy Flip: You found a beautiful sample, although I'd advise you to ease down on the drum reverb a bit, especially the kick. The vocal bits are great as well. The only wrong thing here is the bassline - pitch it up a semitone or a bit less (about 80 cents?). The good thing about the bass is that you didn't make it a slow wobbly one like you sometimes would.
Who Dat: This is actually the only J. Cole song I'm familiar with - I like it, but never bothered to check the rest of the man's discography. Your instrumental has a good sample, maybe a bit too low-passed. However, the a cappella doesn't match the beat (the vocals don't start where they should, either). This is what the decimal BPM numbers are for. The snare sounds a bit too light, maybe add a bit of reverb to it.
@Matt-D
I love samples, but not when they're flooded with vocals like that. I understand that the average Joe cannot get access to the instrumental of whatever oldie you've sampled, but my opinion still stands. I found the 80s sounding fake drums over the 60s sounding soul interesting - nice idea.
Because of the way the samples sound, it's a bit hard to tell the hook and verse apart - maybe put a low-pass filter during the verses. It's a shame the samples are like that because I don't think you would be able to make that guitar in the background louder with EQ and not make the vocals louder as well.