This is actually a tough one.
I'd say Pelle has enormous upside (due to his mix of freak athleticism and size), but Harkless, Sampson, and perhaps Harrison (biggest gunner of this group other than, perhaps, Lindsey) will be more ready to contribute off the bat offensively. I don't think any one of them could've individually been as successful bearing the offensive burden that'll come next year, but collectively it'll be an interesting group to watch. Pointer should be able to contribute as well, but there are only so many shots to put up. The last time I saw Lindsey was nearly two years ago, but the others I can vouch for.