I'm not a fan of LaPorta's fit for Miami. IMO he is a poor run blocker. He's a little too much like Gesicki in that respect to me. He just looks like a lanky WR that gets run through too often. I don't think he'll develop the strength in that area to ever be a +blocker.
Kraft shows much more power as a blocker. He has his struggles their too, but his issues seem more technique based than physical limitation based.
I do think LaPorta is a more dynamic receiver. He'll be better at getting separation. But I think Kraft will be more effective at the type of receptions he'll get in Miami. I envision that the ideal Miami TE will be a very strong run blocker that can be reliable at leaking into the flat or across the shallow middle, present a good target and then break a tackle to get that needed first down. (Basically Darnell Washington). Kraft isn't dynamic, but he has that bowling ball type of running style that's just hard to bring down. I don't imagine many 60 yard TDs, but I do imagine a ton 15 yard plays at the next level.