3-way trade that seems reasonable:
Cleveland gets: #6 from colts, #22 from Bills. 2380 points.
Indy gets: #12 from Bills, #35 from Cleveland, #65 from Bills. 2015 points.
Buffalo gets: #4 from Cleveland. 1800 points.
Cleveland still might have a shot at saquon Barkley if the Giants pass and Denver passes on him. Even if they don't get him they could grab Bradley Chubb or Quenton Nelson at 6. All three are probably in the mix for the 4th overall pick right now and they would get one of them. I think that is the key to making a deal like this happen. They also get to pick 22nd instead of 35th. Cleveland comes out slightly ahead in point value by about 30 points.
Indy would move out of contention for Chubb and Barkley, but they only move down six spots and pick up 35 and 65. They have already picked up two second-rounders from the Jets this year and another next year. They would pick three times in a row in the early second round and also pick up the first pick in the third round. This is a huge opportunity for a team to build a roster that already has a championship-caliber quarterback, Assuming he's healthy. They come out ahead more than 400 points on the draft value chart, 1600 to 2015.
Buffalo moves into the top four and still has two second-rounders and a third-rounder available to them for use or to trade. If the Giants decide not to draft a quarterback, they would be crazy not to move from #2 to #4. And if they have made that decision, I'm sure Buffalo could jump the two spots by offering just one second round pick. It would still leave them with a second and a third. If the Giants decide they are going to draft a quarterback, it means Buffalo gets the fourth quarterback chosen in the draft. They would have to be comfortable with Baker Mayfield or Josh Allen in order to do this, making the assumption that Darnold, Rosen, and one of Mayfield or Allen will get picked before they are on the clock. The only other concern would be the Giants trading out with Denver or someone else like Arizona, but it still guarantees Buffalo with one of those top four quarterbacks. It would also be difficult for Denver or Arizona to beat a buffalo offer if the bills are sitting with the 4th pick.
Bottom line, it makes so much more sense to deal with Cleveland to get up to number 4 first, before going directly to the Giants. That would be way more expensive. Adding Indianapolis to the mix makes even more sense.