Brief editor. It helped that my dad loved it and knew it pretty well too. In any case, it was the first editor I ever took the time to learn.
Like your first language, your first editor molds your expectations. Brief was a keyboard driven, light weight, text focused editor. It was brief. And it had really really good (and brief) help. I no longer remember any of it's shortcut keys or even much about it's interface, but I still remember spending hours navigating through it's help like it was Wikipedia, "oh that sounds interesting." *click* "huh, what's that?" *click* "oooh! that sounds cool!" *click*.
But I was working and schooling in the land of the beast now, so no more Brief. And compared to Brief, Visual Studio is a BEAST! Slow, mouse oriented, cluttered with tool windows sliding in and out from every direction, toolbars everywhere with countless incomprehensible icons. And no help.
I think I did C++ in VS for a full year before I learned about the debugger, arguably VS's killer feature. Isn't the whole point of all this UI mouse driven stuff to make it more discoverable? It didn't work for me. It wasn't my expectation from my Brief days and with the really bad help, I had no way to learn it on my own. I finally learned it from one of my classmates, watching over their shoulder as they tried to fix a bug. My life changed that day: no more print statement debugging!
I learned a lot of Visual Studio after that, but I never liked it, and I never found a good resource to help me learn more about it. I didn't feel bad about it, cause VS was still a slow, ugly, bloated beast. And, I seriously hated it so much I invested ALOT of time configuring Vim to do C# development completely outside of VS.
But that began to change about 3 years ago with VS 2010. It got faster and more usable in some key ways (though slower in others), and suddenly I found myself spending less time in Vim and more time in VS. It also helped that I was doing more web development than winforms or wpf development. Then with VS 2012, it got dramatically better still. I installed VsVim and hardly switched into Vim at all anymore.
It took awhile before I realized I really didn't hate Visual Studio anymore. And awhile longer after that before I realized, "Hey, I bet if I studied this thing the way I studied Vim back in the day, I could wring a lot of performance out of it". So I started paying attention to how I was using it, and I started researching VS tips, VS shortcuts, VS productivity. I haven't found one single good resource, but there's plenty of random blogs with scattered tips.
Then this week, I took a big step. I turned off VsVim. **gasp!**
So far, it's been a surprisingly good experience. Better than I was hoping. I'd like to write up some of what I'm learning here, much like the Vim series. But I'm still working on ideas of how to present it. It's harder than with Vim, VS being such a beast and all...