Following are my really really really personal opinions : maybe totally wrong, please take it with a grain of salt.
When I planned to buy my grand piano, I spent 6 months looking around. I know some people took even longer time. So, here is my humble thinking.
1. If budge is no limit. You can tried
Bluthner : personally tried, and very good.
Bosendorfer : tried, not impressed. But then everyone else say it's good, maybe it's just me or that particular piano.
Shigeru Kawai (not regular K. Kawai) : tried, very good.
Fazioli : not tried. but everyone say it's good.
Hamburg Steinway (NOT NORTH AMERICA Steinway) : If you have way to get it from Germany. European Steinway and US Steinway are totally different animals. Again, not tried, but everyone say it's good.
All above are pianos above $70K USD. (for 6' or above models)
2. between $40K to $70K USD.
Shimmel NWS 213 (NWS model, not regular) : tried, very good.
Sauter : tried. good, but seems over priced.
Mason&Hamlin : tried. good. almost bought.
Grotrian : not tried, but people said it's good.
3. $25K to 40K USD
Shimmel NWS 189 : tried, and bought.
Bohemia Piano 225 : tried, good, almost bought.
Petrof : tried, .. OK, but people say it's good.
Pollmann : tried. but found their upright model make more sense.
Estonia : tried, good (and cheap :) )
Yamaha C7 (only C7, I don't like C5 or below.) : tried, OK, but they got a lot of followers.
Piano that I tried and not impressed (again, it's maybe my problem, not piano's problem)
Baldwin, Haessler, Yamaha S, K. Kawai, Schimmel regular model,
All above description refer to new pianos. There are too many factors will affect used pianos.
I didn't consider baby grand (below 5'6") because I feel they take spaces and didn't necessary produce better sound then upright. Action of baby grand is arguably better. However, I doubt any baby grand will use premium action system. I didn't see any grand under $25K has acceptable sound either, below that money, I would rather buy Pollmann upright or yamaha U3 or U5.
I believe that when people thinking about buying high end piano, they should grab professional players to try the action of the piano. Experienced listener may be able to tell the difference of sound, but it took experienced (VERY) players to know the action system. I doubt if novice player can tell the difference between Renner action and others. Even Renner action seems behave differently in different brand of pianos.
DISCLAIMER to all : my opinions, may be wrong. and don't flame me if I am not impressed with the piano you like.
