I really wanted to give Atom a chance since it gets stuff like ligatures right, but I find its slow startup speed to be a no-go. I simply find in Sublime a much stabler experience and faster startup time, which makes it feel more productive.
I never had any performance complaints while I was actually using Atom, but a while back I made a mistake when generating a text file that turned out to be ~1.5GB. Luckily, it was just one mistake in the footer, so I could take care of it without regenerating the entire thing.
Without even thinking about it, I opened it up with Emacs, went to the bottom, made my changes, and got back out. About a minute later, I saw how large of a file it was and was suddenly even more impressed with Emacs than I had been.
Just for fun, I then tried to edit it with Atom. Nope.
[0] HN discussion: https://news.ycombinator.com/item?id=14821446