When it comes to American Beef I like (in the right order)
1) Mastros, B.H.
2) Wolfgang's B.H.
3) Boa's, W.H.
4) Wolfgang's Tribeca
5) Peter Luger's, Brooklyn
6) Fette Sau, Brooklyn
In BsAs I highly recommend the old Mirasol next to the Sheraton. Unbelievable taste, Las Lillas is more touristy.
If in Cologne, Germany do not miss out on europe's oldest argentinian steak house: El Gaucho.
www.el-gaucho.de Authentic and just great. For germany they started the trend.