Alright, as a fan of all 3 sports and all 3 sports game series here's my opinion:
Madden on next-gen sucked. It wasn't anything new, played pretty much the same as current-gen and didn't look amazing either. Can't really recommend it if you have it for current-gen already. With that said, it's the only NFL game in town since EA bought out the license, so you're stuck with Madden.
MLB The Show is coming out soon and it looks great. The player models look fantastic but the stadiums are also very nice to look at and are accurate. You can now speed up the pitch-counts, so if you want faster games you can start an at-bat at randomly generated counts. The Show plays very well and it doesn't take a lot of getting used to. If you're new to sports games, this one is the easiest to jump into.
I've played NBA 2K since 2K6, so it's suffice to say I love the franchise. 2K14 on next-gen is regarded to be the best sports game for PS4/XB1 right now. The MyCareer mode (where you play as only one player in the team; Madden, MLB, and 2K all have this mode but under different names) now has a storyline with cheesy dialogue, but it's interesting and makes the whole thing less boring. There's whole new presentation elements like interviews at halftime/post-game. The players look beautiful (no homo?) and the animations look as great as ever. I'd recommend this even if you're just a casual b-ball fan since it plays so good, looks, good and is a very deep game. The controls do take some getting used to.