Took some time to think this over and these would have to be my 15.

1. Mp. Grimlock
2. Dotm ultimate O.P.
3. Cybertron Primus
4. Unicron (Black Metal)
5. Dotm Sentinal.
6. Armarda Megatron
7. Transmetals2 O.P.( the big one!)
8. Dotm shockwave
9. Energon Omega
10.Generations Kup
11.Soundwave (G1 Reissue)
12.Cybertron Starscream
13.Ultramagnus (G1 Reissue)
14.Energon O.P. (with the 4 drones attached.)
15.Rodimus (G1 Reissue)