Of course, people will tend to recommend the best places they themselves have dived, and their analysis will be colored by personal experiences that may or may not be the fault of the site.
Some places have well established reputations, but sometimes those reputations are not all that well deserved. A lot of people will tell you that the Great Blue Hole in Belize is highly overrated, for example. (I did a survey on this dive, and found that only about half of the people who have done the dive would recommend it.)
Some places are so huge that even visiting gives only a glimpse of the possibilities. For example, my 12 dives on the Great Barrier Reef represent a tiny portion of the possibilities. I did them on a liveabord on the ribbon reefs that form the true barrier, so my experience would be vastly different from someone who only did the patch reefs closer to shore. (I had a great experience, BTW.)
My week in Fiji similarly only touches on the potential of that enormous reef system, and my experience was clouded by the miserable weather I had while there.
Cozumel has a great reputation, and I have had many wonderful dives there. On the other hand, I have had a few poor dives due to combinations of high current and lousy DMs (one actually led the dive into current until he finally had to face the fact and turn around when we met another group head on.) What if I had only been there once and had the bad experience?
I had a lot less fun than I should have in Bonaire because I was a single diver who some really terrible luck working out buddies for shore dives.
In addition to those places, I have also experienced a few other "name" places, including Thailand, all the Caymans, Belize, Aruba, Curaçao, Florida, and a few others. I will get to Yap and Chuuk later in the year. All these places have their charms, and although I prefer some above the others, I don't think there is any point trying to do any kind of qualitative analysis. I would be happy to do any of them again.
Even if I were to decide whaich of those places I liked best, how can I compare them to the thousands of sites I have never visited?