Much like the Taylor vote for RB, Moore is the easy choice.
But as a Boiler, I'll give you the reason why he might drop quite a bit down the chart by the end of the year...
Last year the Purdue receiving corps was Moore, a couple decent TEs, and a collection of guys who were listed as WR. Which isn't to denigrate them. They were serviceable. But that's ALL they were; serviceable. They didn't demand attention from the opposing defense. They were able to catch the ball when opposing teams double-covered Rondale Moore.
Last year, Purdue had a class of true freshmen WR come in that were all--on paper--far more highly touted than the outgoing seniors, and all of them redshirted. Those guys are going to be ready to show up and explode.
This year, we have a class of true freshman WR coming in that eclipse not only all of those redshirted WR recruiting rankings, but two of them (David Bell and Milton Wright) have higher recruiting scores than Moore. Bell is the 5th-highest recruit in Purdue history, and Wright is 9th (Moore is 10th BTW). TJ Sheffield (a recruiting flip from Notre Dame) is about equal to the best non-Moore 2018 WR recruit as well.
Elijah Sindelar has a cannon on his shoulder--bigger arm BY FAR than David Blough. He can get the ball to those outstanding outside receivers. And if you try to focus on Moore, they'll burn you.
With the amount of talent coming in it's quite possible that Purdue will just spread the ball around too much for Moore to steal the show. They couldn't really do that last year.