Those two are Riley Reiff and Michael Floyd, who both accounted for 13 of the picks in the mock drafts I looked at.
The other three on this list were two apiece.
Riley Reiff, OT Iowa
After losing Demetress Bell to the Philadelphia Eagles in free agency, it's clear why tackle is such a popular pick. Even if Bell hadn't left, the Bills would likely be in the market for one, as their lack of depth was one of many things that was exposed in their collapse from 5-2 to 6-10.
There are questions as to whether Reiff has the makeup to play left tackle in the NFL, as his frame suggests he's more suited for the right side. They need a tackle pretty desperately, though, and shouldn't discriminate against Reiff for that reason. He is a talented tackle, and he could very well prove people wrong about where he belongs on the offensive line.
Michael Floyd, WR Notre Dame
Besides depth on the offensive line, another thing the Bills sorely lacked last year was playmakers at wide receiver. David Nelson and Stevie Johnson are very talented receivers in their own right, but they're not game-changers.
Not, at least, the way Floyd was at Notre Dame. He hauled in 36 career touchdowns for the Irish, and although he may have run a 40-time faster than his tape would indicate, he showed the ability to win matchups on the outside with his size time and time again.
Cordy Glenn, OT Georgia
If the Bills want to add depth on the offensive line, Glenn is a great way to accomplish that. He may be a work in progress, but he has experience at both guard and tackle, making him a valuable asset if the injury bug strikes the offensive line once again.
Glenn is bigger than almost any offensive linemen available in this year's draft. Although he's surprisingly quick, he's still susceptible at times to the speed rush, and therefore may be forced to play inside or possibly to right tackle in the NFL.
Stephon Gilmore, CB South Carolina
The Bills have revamped their pass rush this offseason already, and the next step in rebuilding their defense is to add more pieces to the secondary.
Gilmore is far from a perfect prospect at cornerback, and needs to improve his technique if he wants to make a successful transition to the NFL. He's also not exactly as fast as some teams might like to see in their cornerbacks, but he has ball skills and he's a strong cornerback.
Perhaps he could move to safety, but if that's the case, the Bills have little use for him with Jairus Byrd and George Wilson already comprising a strong duo on the back end.
Luke Kuechly, LB Boston College
Now that the Bills have locked in their two bookend 4-3 defensive ends, the next step is finding the linebackers to finish the puzzle at the second level.
Kuechly looks like the man for the job at middle linebacker in that front, with the leadership and physical attributes necessary to give the Bills another dominant force in the middle. If running backs can weed their way through Marcell Dareus and Kyle Williams, they'll have Kuechly waiting on the other side.