1. Apple's iOS compares quite well, but if you want to maximize stability be cautious about updates until there are some reports (some of the 7.x and 8.x releases were clunkers, though the current 8.3 seems quite good now), and turn off features you don't need, especially the privacy-invading ones.
2. Blackberry. They're still around, and they're rather solid -- provided the device is. (Some of their devices have been clunkers, others solid. Again, take a look at consensus reports.)
3. Nokia/Microsoft S40 devices. You can still find some S40 devices (unlocked and inexpensive), though they are not as feature rich and stretch the definition of "smartphone" downward. I've got an S40 device that, at least once updated to the latest S40 release, is rock solid -- and lasts a long, long time per battery charge. The S40 devices are not long for the world, though, so don't get too attached.
4. If you experiment with Android, I'd stick to the purest form of it: Google's Nexus devices. If Google cannot make Android work well on its own branded devices then nobody can.