I do think Griffy got more gold gloves than he deserved. There was a period, and we are still kind of in it, where the standard for giving out gold gloves was ridiculous. It was basically the above average defender that had a lot of offensive production and was one of the most famous in baseball got the gold glove that year. Thus Griffy got his share of them. On the other hand with him it wasn't like Griffy didn't deserve a good number of them either. He really was one of the best defenders in center field.
For their career in center field I still say Griffy was better, not counting offensive production. If Griffy wouldn't have fizzled out as fast as fast he did it would be an easier thing to answer, but I do give Loften credit for longevity even though it's overrated and you have to be careful of people padding stats.
Offensively Griffy has an enormous advantage, especially considering his peek years and up the age of 30. It's not just home runs; it's the shear numbers of runs that he created. You can't totally separate out offense and defense into two parts when considering a players total worth either (example: Derek Jeter). Keep in mind that center field is a position where the average person at that position is weaker offensively because it's an important defensive position so teams are willing to sacrifice offensive production because of that. For that reason somebody that can be a powerhouse on offense and great at defense at the position gives that team an advantage greater than the sum of their parts over other teams. That is something that has to be taken into account when considering the two.
In a way I'm sort of sad that Griffy dropped off so soon after leaving Seattle in the same way it was bad Frank Thomas dropped off so fast. I remember when people used to argue who was the better player, and who was going to be the better player when it was all said and done, Griffy or Bonds. Now there is no question, it's Bonds(minus the steroid controversy).
The biggest thing Lofton has going for him is the fact we was a good/borderline great player for a good number of years and a good player for a long time. If there were such a thing as the Hall of Very Good he would belong in it. I don't think I would ever put him up in the elite category at any time in his career however.