Wow, sorry for the late reply!!! For us, the biggest thing was the action. We didn't know anything about grands, so we just went w/ something old and cheap, but that came with a heavy action which ended up starting to hurt his fingers, so it was imperative to get something different. Actually, many old pianos actually become
lighter to play, since the hammer felt gets worn away, and the action parts (felt bushings, etc) become worn and looser. YMMV.
We ended up w/ a Baldwin M, which we will also need to change up, because that one does have truly too light an action for him now (a bit of a pendulum swing too far). We (erm, I mean,
he) has played dozens and dozens of pianos...including some of the absolutely nicest pianos on earth...tons of Steinways, Bechsteins, Mason & Hamlins, Bosendorfers, Shigeru Kawais, even a Fazioli!
His absolute favorite out of all of them are the Estonias, which are a really wonderful 'European' piano brand, meaning very musical and singing. We've heard a couple of L210s and an L190 that had just a mesmerizing, heavenly tone, and they have Renner actions as well. They are a bargain next to a used or even slightly new Steinway, but $30-50k ain't nothing to shake a stick at.
We haven't really liked the Masons we've played, oddly enough. They sound brawny (not bad), but it's just not our preference, and most of the one's I've seen are either poor rebuilds or built during rough times for them (70s-90s). Didn't care much for the restored Bechsteins, either. The new ones may be a different animal. Haven't tried a Bluthner. Schimmels, Grotrians, all nice European pianos to be evaluated on a case-by-case basis.
I really love the older Baldwins (60s-80s) for their sound and bang-for-the-buck, but the issue is that his piano teacher (who is
very good), doesn't like them
at all. She favors Yamaha, and we've played some nice ones as well, but finding one without a 'too bright' or harsh tone (for us) can take some time. Her primary concern is the playability, and she's not wrong from the aspect that any 40 year old piano is going to need a total action overhaul.
My perspective is that a nice Baldwin R or L from their golden era is going to be so cheap, that you can get it, replace the bass strings and either rebuild the action w/ Renner parts (and new hammers/shanks) or simply replace the action w/ a WNG composite action and basically be at or under the $$ for a new entry level piano and you now have something way better. An R or L that is in good condition is probably going to be just fine in the pinblock and soundboard dept.
If the piano is going into the home, a 5'2" - 5'10" is probably going to be your best bet, with the latter probably bridging the gap between tone and volume. Too short and the sound in the bass is compromised, but too big, and it can impair a player w/ the volume. 5'6"-5'8" is the goldilocks size.
If size is not a problem for you, then a used Baldwin SF-10 or older Kawai GS-30 are some of the best in the world for the price you can get them for. A smart way to do it would be to find one that has been recently and expertly overhauled in the strings/action dept, because that labor is expensive up front, but cheap 2nd hand.
Right now, we are cautiously looking for either a Japanese Kawai or Yamaha C series (probably a C1 or C2), but secretly hoping for a used Estonia to pop up. If it were up to me, I would get a 60s-70s Balwin R or even an L (better scale design) as a 'core' piano as long as the soundboard, bridge and pinblock checked out, and then have a tech rebuilt it w/ new strings, agraffes, and rebuild the action to whatever we want/need. I'd hear a resounding NO from the piano teacher, and right now we don't have a trusted tech, so that is probably not the route, at least
for now...ha!
I know this is probably way more than you wanted, but there you go. If you price range is under 15k, a top tier smaller used piano that has been recently serviced would be the ticket.
This right here is my jam, and it sold for less than a brand new 5' budget piano that we've been recommended:
A whole bunch of planned landcruiser mods (several of which I have parts for) are no longer on my to-do list.
