Depending how you classify combiners I have a few complete combiner sets.

Encore Devastator, Encore Predaking and a 1990's Classics Menasor from G1. Menasor is no shape to display. My Devastator and Predaking are both in combined mode.

From Masterforce I have Ginrai/God Bomber combined.

I have JRX and Optimus/Magnus from RID. JRX is combined Optimus and Magnus are in truck mode.

From Cybertron I have Optimus/Leo Convoy (Universe) and Megatron/Nemesis Breaker. All in uncombined robot modes.

And from the movies I have Buster Prime/Jetfire and G1 deco Devastator. Both in combined mode.

I'm thinking about picking up a Anime Devastator and Encore Bruticus.