I have always loved Yamaha gear. I find their user interface intuitive and easy to work with. I have a Yamaha SY99 and love it. I actually added an E4x sampler to my rig. If I didn't have the SY, I may have spun for the EX5. If I only had a controller keyboard or other synth (ie SY77 or Kord O1/w) I may have just added the Ex5R.

But my needs were truly sample based. In which case you should definitely go with EMU. But if your needs are more diverse and you want a pallet of synthesis, then go for the Yamaha EX5. Easier to use, maybe that's just because I'm used to Yamaha logic.

Regards,
Jason