Both Dragon*Con and San Diego Comic Con are massive gatherings, but they are drastically different conventions. Comparing them isn't easy or even necessary. If you can only attend one of these two conventions, make sure you pick the one that best suits your interests. I've broken down some deciding factors below, excluding price, as neither is cheap and the actual cost will depend on how far you have to travel and how early you start making arrangements.Best Con for Cosplayers: Dragon*Con
If you're a cosplayer and you have the means to get to Dragon*Con, do it.
The cosplay scene at San Diego Comic-Con isn't great in comparison to other Southern California conventions I've attended (if you like costumes and are in L.A., go to an anime convention), and it's downright terrible when held against Dragon*Con.
In San Diego, you'll often see people dressed in costume only to find out that they are part of a street team for some TV show or movie. Sure, there are some great cosplayers who attend, like the group who formed Gender Bent Justice League and the guy who showed up at The Venture Bros. panel dressed as Plugface, but they're in the minority. Geeky t-shirts and jeans or shorts is the standard dress here.
At Dragon*Con, though, at least half the crowd is costumed (a conservative estimate). We're not talking run-of-the-mill costumes either, although there were an awful lot of Poison Ivies entered into the convention's beauty contest. My roommates at Dragon*Con dressed in Nerfpunk, which is sort of like steampunk rendered in bright, Nerf colors. I shared an elevator with a guy dressed as Buffalo Bill from Silence of the Lambs. Not only did the obscure Plugface character make an appearance, but we caught him at The Venture Bros. Blog party with Mommy Longlegs. Hell yeah!Best Con for Toy Collectors: San Diego Comic-Con
After Dragon*Con, I talked to my pal Marc Illagan of The Venture Bros. Blog. He goes to both San Diego Comic-Con and Dragon*Con and is torn between which one is his favorite. Both cons have their advantages. One of the plusses of SDCC, he notes, is that the exhibit hall in San Diego has a much better selection of toys and collectibles.
Dragon*Con had two exhibit halls, plus one artist alley, which I visited at this year's convention. Still, it's only a small fraction of what you'll see at SDCC. Since the San Diego con is a major, international event, many companies release items that will be exclusive to the convention. The lines are long, but the toys are almost guaranteed to become collectible.
Moreover, SDCC is a major event for designer toy artists and the selection of vinyl figures is excellent. This year, the first Designer Toy Awards took place during SDCC. I didn't notice any sort of designer toy presence at Dragon*Con.