The main problem is that what makes someone better is a very subjective line to draw. Guitarist A might be more technically skilled than Guitarist B, but Guitarist B might have an unusual technique that results in a very atmospheric playing that Guitarist A doesn't achieve. I've heard several artists where they might not be the best when it comes to singing, or playing their instrument, but they know how to compose their songs. And I know artists who have all the benefits of being skilled at what they do, but the end result isn't very fascinating.
If you compare Dream Theater (a successful band of over 30 years) against a random garage progressive rock band who just started, you could easily draw the conclusion that DT are probably the more individually skilled band (with all the experience of playing), but if that random garage band made an album, some people might like it more than a DT album. So it's a very hard thing to draw a line with, because while we can discuss who has the more talent and stuff like that, it's pretty much impossible talking about quality as a measure, considering we all have different criteria for what qualifies as such.