Hey, I realize I'm a bit late to the party here, but if you're still looking for a seed with Jungle, Mesa, and Mushroom Island directly accessible from spawn, you might try "-6260648655964461644." The inland sea on this one gives you access to all three if you don't mind some sailing, as well as Ice Spikes and a variety of other features. Notably, the mesa near the mushroom island includes a decent sized Bryce Mesa (~400x~300 at its widest axes, I don't know how to give you a block count.) I'm liable to try this one myself at some point.
Just don't pick this seed if you were hoping for a witch farm near your base, nearest I can find to that mushroom island is in around 4k west-southwest at -5288 -824.