I really like BSR's for daily users. Heat rings mean they work well on all cooktops. No brand markings make them largely affordable. Long manufacturing time makes them easy to find. And they are a good middleweight for heat retention. All the same can be said for vintage 3-notch lodges, and even the 1-notch lodge that I keep an eye out for.
Now as a cast iron aficionado, I like anything with an outside heat ring. Mainly older Wagners and whatever else I can find under $100 with an outside ring. I found a crusty Chicago Hardware diamond #8 for a good deal that cleaned up beautifully.
I have befriended a cast iron picker in my area who likes early Wagners and have picked up 4 different wagners from him with an outside ring. So while Wagner smooth bottom are probably my least favorite of the vintage varieties, Wagner OSR's are quickly climbing to my #1 pick.