BOSENDORFER. These are the most expensive and probably the best. However many pianists prefer the tone of some of the old German pianos such as BLUTHNER, BECHSTEIN, and STEINWAY. There are some very good pianos from the far east notably YAMAHA and KAWAI. But this is just scratching the surface, good pianos are manufactured in U.S.A. (BALDWIN) France, the Czech Republic (PETROF)
In the U.K. Look up BROADWOOD and BRINSMEAD.
Here is a more comprehesive list of renowned piano makers.
Allison - (English)
AutoPlayer - (English)
Beale - (Australian)
Bechstein - (German)
Bell - (Canada) - (unknown)
Bluthner - (German)
Böesendorfer - (Austrian)
Boyd - (English)
Brinsmead - (English)
Broadwood - (English)
Challen - (English)
Chappell - (English)
Chassaigne, Freres (Spanish)
Collard & Collard - (English)
Crane & Sons - (English)
Danemann - (English)
Doherty - (Canadian)
Carl Rönish,Dresden (German)
Eavestaff - (English)
Ennis - (Canadian) -
Erard - (French)
Grotrian-Steinweg - (German)
Kemble - (English)
Lipp - (German)
Monnington & Weston - (English)
Murdoch,and Co - (English)
Pleyel - (French)
Ritmuller - (German)
Rogers - (English)
Rushworth & Draper
Schiedmayer - (German)
Steck - (U.S.A. and English)
Steinberg - (German)
Steinway - (German)
Strohmenger - (GERMAN)
Weston & Co - (English)
W. H. Barnes - (English)