I understand why there are people who are skeptical of Jackson. His accuracy is subpar, he floats too many passes for having such a great arm and there are some mechanical adjustments he'll need to make (mainly with how he uses his lower body on certain throws). On the other hand, he's very comfortable under center, he shows poise in the pocket and he generally makes good decisions - three things that you would never associate with a guy who needs to change positions. I don't want to play the race card, so I'll say this - any "expert" who thinks he can't and shouldn't play QB in the NFL is not somebody worth listening to. He was literally a one man show at Louisville so I can't rag on him too much for the sub 60% completion rate. I do think if he was taken top 5 and expected to start right away, he'd be set up to fail. If there's a team that can afford to wait on him, I think they'll reap the benefits for a long time. He's a comparable athlete to Michael Vick, but he's a better QB.
Mayfield's alright IMO. He has that Oklahoma QB stigma working against him and he has the dreaded combo of being both a very short QB and a QB who played in a spread offense. I think that he was initially underrated and now he's become a bit overrated. He's not bad, I don't see any red flags that make me think he can't succeed, I'm just not a huge fan. I'd certainly rather have him than Mason Rudolph, though. Rudolph has looked like trash every time I've seen him play. Let me put it this way, Landry Jones has a better arm than Mason Rudolph.