I'm a fan of the external socket type dropouts. Partly because they look like a lug which I personally like, but for the even greater reason having to do with ease of build. As someone building in the garage without a lot of hard tooling I find it challenging to get tab style dropouts properly aligned when brazing. Also, with the external lug design it's easy to sweat flow the braze into the gap just like a lug; feed in the filler until the joint won't readily take anymore and you then know there is 100% penetration all around.
As Clint says, a man's gotta know his limitations. I'm confident with brazing lugs and all, but less so with filling big gaps like on a dropout.
P1040221 by
nessism, on Flickr