This is just one person's opinion. In my opinion FF7 was the best and VI was a close second. As for Xenogears I will have to check out. Many people criticize the voice acting but I really don't think it's bad at all. If you look at Kingdom Hearts and Kingdom Hearts II I believe they did a very decent job with voice acting. When I first heard Sephiroth on KH I was freaking amazed and it did not ruin the experience for me at all.
That is MY opinion. You guys have different opinions. In reality, even after reading this, do you think people are going to base whether a remake will be done based on what you 'think' will happen or your faulty predictions? No. The fact still stands that it is still a possibility. No conclusions can be made based on your incomplete analysis. Therefore everyone who reads this knows that there is still a possibility that it will be remade in the future (for the PS3 or maybe future systems).
The fact still stands that Nomura has stated before that if he finds the time, a remake would be interesting, and also Kitase has said that hope fora remake is not dead because many of the staff working on XIII, including themselves, are FFVII fans and many would love to work on a remake. According to their statements back in 2007, they were not currently working on a remake but there is always a possibility.
Everyone has their own opinions. I just decide to look at the facts and base my thinking on just that.