I will take the plunge since I have recently played ALL THREE of them.

Estonia 190: Bright and loud. It's a lot of piano for its price. BIG sound, good if you have a BIG living room. Very "sensitive" action, but I personally find it hard to play pp/ppp at the treble. (Personally, I also find the key surface too slipery with that "cheap plastic" feel.)
Yamaha C3: Good action, good sound in studio/home environment. Good quality control from Yamaha for its C-series in general. Has the signature Yamaha brightness but not too loud as to overpower a small studio or living room. Has "depth" in the tone (but lower register's tone will "break" if you drive it to the fff range). It's a very solid choice. (Choose the Ivorex key surface if possible so you won't get the "cheap plastic" feel under your fingers.)
Petrof III - This is beyond bright, it has a lot of "metalic" quality to its sound. Otherwise, a solid, fine piano with a lot of power, but probably with a narrower dynamic range than the other two overall. If I recall correctly, the keys and pedals felt a little shallow for my habit, but that's just me. If cymbals and bells and triangles and glockenspiels appeal to you, you will likely like Petrof.
All three are very good choices that you cannot go wrong with. My rational analysis says that in sum they are all just as good (without factoring in resale value and warranty -- of which Yamaha probably has a slight edge). It's just a matter of finding one you yourself like the best. (Of note, one Yamaha C3 will likely sound and behave like another C3 or at least can be made to sound like another C3 with very little tweaking, but this cannot be said of Petrof or Estonia. So if you find a particular Petrof or a particular Estonia you like, that's the one you have to buy. Because the next brand new Estonia 190 or Petrof III from the factory may sound/behave rather differently. If you find a C3 you fall in love with, don't be shy to insist on getting that particular one either, whenever possible.) Frankly, if you have the time, the best way to proceed is to play as many pianos as possible, even multiple pianos of the same make and model, until you find one you love or until you're sick of trying out more pianos, at which point you pick one that you like the best (or hate the least) from those you have played.
(All your three choices veer to the "bright" side of the tone spectrum, with Yamaha being the most "mellow" of them all. If you want something even more to the "mellow" side of the spectrum, take a look at a Kawai RX-2, RX-3 or RX-5. RX-2 and RX-3 should be cheaper than the C3 and the RX-5 slightly more expensive. The Knabes and Young Chang/Pramberger series also have 6'+ grand pianos in your price range.)