I don't know if this is the consensus now but the common view back when Mega Collection released was that Sonic Jam was a far superior collection. The extra games you get in Mega Collection (Dr. Robotnik's Mean Bean Machine, Sonic 3D Blast and Sonic Spinball) don't really add much and the bonus features are totally lacking compared to Sonic World. Not to mention straight ROM ports versus the ground-up ports in Jam which allowed Sonic Team to add some extra gameplay options (difficulty levels, a proper save system, the ability to turn off time-out, time trial, Special Stage runs, spindashing in Sonic 1).
The flip side that I've come to appreciate more now is that the Mega Collection ROMs do
play better than the Saturn ports, with Sonic 2 in particular having some odd slowdown issues and the general problems that come from using CD audio.
Also no one in America had a Saturn anyway so it was kind of a moot point for most people. Still, there was one thing that was cut from Mega Collection that would have made it the easy champion:
