Two questions to ask before buying a piano: what is it used for, and who is going to use it? Question one - is it for learning (taking exams or not?), just playing, performing etc. Question two - for beginners (taking exams or not), intermediate player, performer etc.
As nikolaiski said, you need to try it for yourself. The tone is one thing, but I think one of the main thing is touch and response. If you are going to use it for practice (esp for somebody taking exams), and esp so if that person is younger, you may want a piano to build finger technique and strength (hence a piano with a heavier response, but you'll also need to watch for weight that may be too heavy if the player is very young - you don't want to cause injury). If you're seasoned player and a performer, lighter touch and response is probably something you want. That's my first filter when choosing a piano. After that comes the tone and sound.
Age is something arbitrary. Many old pianos still sound and work great. New does not equal to better. Also, older models doesn't make it any worse (or better) than newer models. Of course, some old used ones will undergo wear and tear, which you need to take into consideration. My old 36 year old Kawai underwent an entire overhaul once and it's still working very well. Now that I'm not in Singapore, I got a Yamaha YU series (overseas model) mainly so the touch helps my kids build their finger strength and techniques - ie a practicing piano (although I would personally choose a very different model if it was just me playing).
I recalled ages ago, my piano teacher's studio lies a Petrof Grand piano, which I play every week during piano lessons. The response so heavy that my fingers could hardly move. But it was good for me. She had another upright - an IBach. When I played that, the weight was so light (totally opposite to her Petrof) that I couldn't get used to playing it (and played terribly). I remembered before my Grade 8 exam (exam was in her home studio), half an hour earlier I wanted to warm up and practiced on her IBach. But because I was so used to the heavy keys of her Petrof, I couldn't play at all! I wondered what happened to me and whether I was going to fail! Good thing the exam was on her Petrof Grand - which I was already used to. That was when I was a student. If I had a choice now, I would prefer the IBach over the Petrof anytime. But for the sake of my kids, I would go the opposite.
). 
