When I had finally decided to get the Energon Omega mold, my choice really went to Sentinel since I liked his colorscheme a lot better. Unfortunately, he seemed somewhat hard to get, unless I was willing to shell out big time -- which I wasn't.
One search on e-bay went wrong. I made a typo, and I wasn't the only one
And so I got my hands on a cheap E Omega Supreme; after international shipping I had to pay $ 23 (approx 19 euro). Of course, the catch was that he wasn't complete: no missiles, no transformable head and he missed two little panels on his left foot (something I didn't notice until I got Sentinel). But I had Omega Supreme.
And then, a few months later, I did manage to get a reasonably priced Omega Sentinel. And I loved him. Such a cool colorscheme. But as I put the two of them together, I quickly saw a way to really improve on Sentinel. And all it took was a screwdriver and some time.
The same parts that were orange on Sentinel, were red on Supreme. I don't mind orange, but I just felt it looked stupid on Sentinel. With the red parts from Supreme he looks a lot better IMO. (Just a shame my Supreme came without a head, because it means there still a little bit orange on Sentinel: his head.)
As for Supreme...well, he looks okay as well. Funny thing is, with the orange parts from Sentinel, Supreme looks more geewun accurate -- and I feel that orange works better with yellow.
It's a very simple swap and I'm surprised I have never seen or heard that others did it as well. (Maybe because it's too simple