I'm in the "but mah immediate mode" crowd, so thanks for the condescending tone. I like immediate mode and matrix stacks and all the nice stuff compatibility mode provides because they are convenient even if they aren't fast. Quite often what you want is convenience, not performance and adding a usually badly documented 3rd party library that might be dropped next year (or whatever) or break its API is not a desirable solution. Especially when the entire point is moot since OpenGL 1.x/2.x and 3.x/4.x compatibility isn't going anywhere any time the next couple of decades - at least.
Besides the parent post is about what someone's favorite API was so i also added what my favorite API is. D3D9 isn't any more deserving to be someone's favorite API than OpenGL.