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.
ligatures in source code? It seems as soon as I use a non-fixed width font, then indenting and other code formatting becomes tricky. Bjarne Stroustrup uses a proportional spaced font in his C++ book and I hate it.
Yes, specifically ligatures in fixed-width fonts like erik-g mentioned. My personal favorite is Hasklig[0], which is based on Source Code Pro.