Good OP
@LoyalRam - Before i get down to the reasoning IMO - I like both picks - they compliment each other fantastically.
Ok so here goes:
Kupp - IMO is the most pro-ready WR in this year's class his on-field effort and his off-field prep & training regime speaks volumes of this kid - He wants to succeed. His route running is crips and well developed and hands are beautiful and he consistently finds daylight after the catch - something which is priceless in the NFL. His game speed is fast (faster than his combine times anyway) but I think it's his understanding and technicality is what gets hime the extra yard or two on cover. I have high hopes on Kupp becoming a QB comfort blanket. That dependable guy that will work for the first down.
Reynolds - Has great deep speed and it a rangy guy that gets up there and turns the 50/50 ball into his favour. He'll need to put some work in the weight room to add a bit of strength to compete with physical corners in the NFL, but thats something that can be remedied. He is a little raw I guess and his route tree / running and on-field spacing needs to be worked on, but I think the sky's the limit with Reynolds IF he can put the time in and coach Yarber can get the production out of him. I've read a couple of pro-scouts comment that he could be "the most productive receiver in this class in 3 years" and "in a couple of years he could be the steal of the draft" - but I can't find those reports right now!
Basically:
Kupp - is a matured, solid NFL-ready pro, ready to run and slide right into the starting line-up day 1 - but he may have hit his high ceiling already.
Reynolds - could be that elite #1 guy, in a year or two given the right nurturing to reach his sky-high ceiling.
You draft Kupp first as he's a surer bet to be a success on day 1 whereas, at the moment, Reynolds needs a little time and work to mature into the elite target he could be.