Silly question, perhaps, but what is your budget? Are you looking for new or 2nd hand? Have you got a local Meridian Premier Partner? 2nd hand prices, from memory-ish are around:

5Ks : �900 - �1500
5K2s : �2500 - �3500
6Ks : �4500 - �5500
7K2 : �9000+ ?

Those are for L/R pairs ... and you may well want a processor and a centre speaker for the seductive and inimitable Trifield (q.v.). I get my best 3D image (which you mentioned) that way.

Only the 5K2s and 7K2s are available new. I've left off the 7Ks as I can't remember their resale prices - worth searching the restaurant perhaps. There's also a size-chart somewhere so you can see the relative scale of the things too.

Welcome to the start of your journey, Grasshopper.

As others have said, you may want to audition (especially if you are unconstrained by price). Can you get to the Bristol Sound & Vision Show in 3 weeks time? Sevenoaks Bristol are hosting an M event at their shop. You could hear some of the very, very latest Special Edition kit there.

Duncan