In my Batman display I use both DCUC and DC Direct. The Hush line goes especially well with DCUC.
Agreed. I doubt Mattel will ever give us a Commissioner Gordon or Alfred Pennyworth in the DCUC line, so the Hush versions make wonderful substitutes. Hush Poison Ivy is a very nice looking figure too.
I also like DCD's Long Halloween Mad Hatter. And of course the Crisis Power Suit Lex Luthor is much more accurate than the DCUC version if you want a Super Powers-ish Power Suit Lex.