If this was a roto league, I think it would be tougher to decide, but in a points league I looked around and I think both A-Gon and Longoria both are more valuable in a points league than a standard roto. A-Gon especially seems to pick up more value in the points league.
In a points league , I think you'd get the best player but you would net out potentially two top-30/40 guys and the other owner would net out up to three, with A-Gon and Longo valued a little higher.
I think I'd have to pass on that offer, but would still try to find a way to grab Verlander since he seems willing to deal him and Verlander is even more valuable in a points league. I suspect he's valuing A-Gon pretty high, so I'd try Lee/A-Gon for Verlander/Kinsler. He'll probably reject it and then I'd counter with Lee/Longo for Verlander/Kinsler/Seager (or Freeman) and see what happens (probably not, but you never know). Otherwise, I'd look around or go Lee/someone else not listed for Verlander where you're the one giving a two-for-one.
I know it looks like a nice trade, but I think you can do better.