After driving myself insane with an unreliable Leonardo, I narrowed down the problem to its serial port. Namely, it's not a true serial port, but some sort of simulated monstrosity that can't be reliably reset. This makes uploading sketches immensely difficult. I found that neither Arduino-Makefile nor the Arduino IDE can reliably upload sketches to a Leonardo, and succeed only 10% of the time.
It took me awhile to accept just how terrible the Leonardo was, because before this, I had only used the Uno and Mega, which are extremely reliable. They've always "just worked" for me, so I couldn't understand why Arduino would release a board as unusable as the Leonardo. I've since realized the Uno is so reliable, in part because it has a more complete serial port, and don't use the dreaded 32u4 chip and its fake serial port that doesn't support the DTR or RST pins.
That said, which Arduino's have a real serial port? Is it only the Uno and Mega? After months of banging my head against a Leonardo, I want to avoid anything else that uses the Atmega32u4 chip. Unfortunately, looking at all the various boards, it looks like many, especially most of the newer ones, use the 32u4.
Am I missing something here? Everything I Google an error uploading with avrdude or the IDE, the results always mention problems with boards like the Leonardo and their unstable serial ports. Why does Arduino keep using the 32u4 chip if it's that unreliable?