Trilogo's are popular at the moment - especially those in good condition and limited bubble damage. However, I don't think that it is possible to say that there is a pattern right across the board.
Some figures are pretty common on ROTJ yet harder to find on Trilogo - Leia Boussh springs to mind (and obviously Madine!) so these will sell for more - however some of the more common figures - Klaatu, Nikto, Ree Yees, Prune Face etc cost the same on Trilogo & ROTJ
In general I think condition is key - especially when it comes to Trilogos - last year a Ree Yees (quite an easy Trilogo) sold for over £150 because it had a minty bubble