I'd be thinking either the MM6 or the Fantom XA. The MM6, if I'm correct, has many of the sounds of the Motif series, but I'm not certain that it's sequencer is a fully featured workstation sequencer.

Probably ( and of course this is my personal taste ) I might favor the Fantom for pure synths soounds vs the MM6. All I can base that on is that I have a Motif ES, and I like the acoustic instrument sounds more than the synth sounds in it, enough to the point that I recently added a Korg M3, mainly for it's synth voices and the karma features.

I demoed a Fantom a few tinmes and thought it also had better synth sounds overall than my ES does.

Good luck with whatever you decide

Zoot