Shockwave and Megatron seemed evenly matched, with Shockwave having one win over an injured Megatron and a rematch ending in a draw. Scorponok got the better of Shockwave towards the end of the Marvel run. And Thunderwing seemed about as powerful as any of them, doing standard leader class stuff like pwning Grimlock and groups of rank and file Autobots, and he also nearly beat Optimus Prime to death with his bare hands (To be fair, Prime was holding back because Thunderwing was possessed by the corrupted Matrix, but Optimus is still durable enough to take Scoponoks attack point blank with minimal damage, yet Thunderwing caused tremendous damage bare handed.)
Ok, no doubt Shockwave is badass, but Scorponok is much bigger, and Thunderwing? Thunderwing had a pretender shell, and the Matrix! Not to mention being quite powerful himself.
Scorponoks big, and he did dominate Shockwave, but Megatron probably has the best ranged weapon. His big assed fusion cannon took down Predaking!
And not only that, he can tap into the power of a black hole, although it's a dangerous trick (He seemed pretty certain he could take out Auntie and survive the ordeal, as did Optimus Prime..)