I bought Fanatec Carrera wheel for GT5, when it came out. Prior to this, I have been using Logitech DFP for GT4, but that was a long time ago, so I couldn´t make any direct comparsions. Still the wheel felt much better in every way, even if a bit noisy. If I´d have any proper wheelstand or rig to attach it to, it would be even better. Just clamped on the table, i had problems with my shifther constantly moving the wheel, when shifting.
Now regarding the Fanatec customer service.
I also had problems with the standard pedals. After a month or so, the gas pedal was getting flimsy, resulting in about 10% permanent throttle in GT5. I´ve trided to contact customer service on fanatec website, but with no luck. Sadly (luckily) Thomas was (or still is) very active on this forum, so i PM´d him, he gave me instructions and in about a week, i had the new set of pedals at my house. That was about 3 years ago, so things may have changed since then, but i wounldn´t have a problem buying another product from Fanatec. I sold the wheel shortly after (because GT5 SUCKED and it was the only game, i had it for).
The wheel itself was very nice for the price and with proper mounting and better set of pedals, it still could be a great option for you. The adjustment option is a HUGE plus on the PS3, so just based on that, I would recommend buying Fanatec. Sadly, i never had the chance to compare between G25 or even G27.
Now, I am considering the 911 GT3 RS, but not just for GT6, but for pCars, Asseto and some others. The only thing, that is holding me back right now is the unclear situation regarding the PS4 support..as soon as more information emerge on that, I´m going for it.
Q: So far, the only wheel I´ve heard of, that automaticaly comes back to center possition when drifting is the T500..can somebody comment on that? The Carrera wheel didn´t do this.