Depends what your looking for in a phone. I bought my wife the Razr M and she loves it, she came from an iPhone. Its a bit bigger but perfect for her because she has smaller hands. She gets great battery life on 4G and the phone for a "cheaper" phone is great. It has the Jellybean update so the phone is really smooth.
Ingenieur7, the camera on the Razr M also has burst mode.
The screen on the GS3 has more PPI because its a bigger screen. The smaller 4.3" screen is just as crisp.
The radios in the Motorola are better so signal strength is better, there for GPS would be better and faster on the RAZR M.
Battery life on the Razr M is much better than with the GS3. Smaller phone + smaller screen = better battery life
According to phone arena the US versions both have the same processors in them so I'm not sure where Ingenieur7 is getting his information from.
Touchwiz has alot more crap that clutters up Android. Motoblur is very minimal, its almost like stock Android.
I guess the bottom line is if you want a phone with 4.3" screen or 4.8" screen. They are both good phones and they each have features the other doesn't. One thing I will agree with is the camera on the Razr isn't as good as on the Neuxus but Battery life will beat out camera quality any day in my book.