Android emulator would be the worst one for me. To be honest, I haven't used that many dev tech yet, but this thing gave me nightmares.
The one provided by Android Studio sucked ass horribly, and it didn't let me use my dedicated graphics chip (nVidia 740m). If I used it the emulator either my apps would crash or not start at all. After some googling, I found out that this was a common thing more or less...Using virtual graphics on it was slow, sluggish and rubbish with ~1 second delay with clicks and scrolling and shitty screen changes proccessing.
Using Genymotion was no better so I just stuck with the one provided by Google for the time being.
I have to add that most of those apps were tutorial apps, and only 2 were semi-serious.