
Rich has given you very good advice. If you can't tell the difference between these pianos, spend less money. They are very different, but most importantly, you need to develop your palate.
It seems to me you have narrowed your selection to well marketed pianos, which, IMO, is a very dangerous and naive parameter to choose an instrument.
Baldwins, for example, in fact vary wildly in quality, due to the historic instability of the company and most importantly its work force. These pianos are well known for having frequent major lapses in craftmanship (I mean the execution of the design, rather than the design itself). Querendo invenietis.
Steinways, IMO, fare not much better. I am not a big fan of Steinways, so bare that in mind while I bash them. Quality control in uneven, which is to be expected from their production volume. Fazioli, Steingraeber and even Mason & Hamlin only make a fraction of the number of pianos Steinway puts in the market every year; part of the reason is because they look at them before they put them in a box. There are much better pianos out there for less money (short list: Estonia, Bluthner (even Irmler, their less expensive brand), Mason & Hamlin, August Foerster, Kawai).
Which leaves you with the Yamaha. I like Kawai in every respect better, and they tend to be cheaper, so at least check those out.
And Estonia is making really good pianos right now. Rather than reading about them go play one.
Good luck,
H (in a good mood with IU at 3-0, first time I can remember)