Ok, I'm going to buy a used bass, and let's say that all theese guitars cost their MSRP, and I can get them for 350 euros used.
The choice is:
Ibanez SR505, it's around 650 euros, 350 used.
Yamaha BB G5, discontinued, 350e used
Ibanez ATK new is 550e, 350 used.
Which one do you recomend and why (please specify the why? part)
For US players: imagine that instruments cost their MSRP, and i get them for $350; I know that US players are always doing
when they see European prices 
All the basses are in great condition, setup and playability.
The choice is:
Ibanez SR505, it's around 650 euros, 350 used.
Yamaha BB G5, discontinued, 350e used
Ibanez ATK new is 550e, 350 used.
Which one do you recomend and why (please specify the why? part)
For US players: imagine that instruments cost their MSRP, and i get them for $350; I know that US players are always doing
All the basses are in great condition, setup and playability.