The purpose of this site is to talk about some of the hottest MMO Gold Sellers, and what better way to determine the best around than to put them side by side and see who comes out looking the best? I won't go as in depth as I normally do for these sites, because I've done so elsewhere, but this should give you an idea of each sites strengths and weaknesses, and hopefully help you decide which one you want to buy from the most.
Games: WoW (US, EU), AION, WAR (US, EU), AoC (US, EU), EQ, EQ2, FFXI, Lineage 2, Vanguard
IGE is the site I use for most of my purchases. They usually have competitive prices and high availability, and gold for all the top games. I used them for years without issue, so I'd say they are very safe. Recently, SwagVault beats them on pricing a lot of the time.
Games: WoW,AION, Lineage 2, FFXI, Guild Wars, Matrix Online, WAR, CoH/CoV, AoC, Atlantica, Archlord, Dark Age of Camelot, Darkfall, D&D Online, EVE Online, EQ2, KAL Online, LotRO, Luna Online, RF Online, Silk Road, SW Galaxies, Maple Story, Vanguard
SwagVault.com is, like IGE, a big, safe site, with competitive pricing. In addition to having some of the lowest prices you'll see on a non-scam site, they have gold for TONS of games that other sites don't. I use them more consistently than any other gold site on the list.
PS: If their Quick Shopping thing in the middle is giving you trouble, go to the game using the sidebar instead. The Quick Shopping menu in the middle of the site often acts glitchy on certain browsers, turning people off the site, but the sidebar works fine. It'd be too bad if you missed out on trying this site because of something so silly.
UPDATE: This site died. Good riddance, given their high prices and dubious reputation.
Games: Too many to list
IGXE is another popular gold site, and this one has even more choices than SwagVault. That said, I don't really care for this site. They have a lot of problems with glitches, and their customer service is dodgy as hell if something does go wrong.
I'll add more sites after I have reviewed a few more sites individually, so look forward to more top gold sites to come!