I've got both Titanium G1 UM and Titanium G1 Rodimus, and I like them both, but to look at, not necessarily to play with. The reason I like them is at they're more in scale with G1 Optimus and at the time I picked them up (pre Classics line - I think it was Universe ~2007) I was only looking to have G1 in my collection. Also UM apparently has a cavity for a matrix in his chest (I haven't checked it as mine is kept MISB but I imagine that the matrix from Hybrid style Convoy would fit). They're certainly something different for a display shelf if you can find them at a reasonable price - last time I checked UM was goin for ~$150 USD, waaay more then I paid for him.

And I don't think it's been suggested yet, but THS-02 Hybrid Style Convoy?