[rcxdude]

I2C has caused me probably the most grief out of all the buses, as it's been the most painful to work with when designing the schematic (because even with only 3 devices you have to deal with address conflicts), initially writing the software (because the specification is quite lax on what can happen when, inevitably the interface between hardware and software is quite complex and a lot of it is very latency sensitive. A lot of hardware for it is quite buggy or just poorly designed as well), and in terms of ongoing bugs and issues (because of said latency sensitivity and propensity for locking up).

I try to avoid it as much as possible. If I need a peripheral, I prefer SPI, if I need a bus for connecting devices I control, I use CAN. If I'm connecting two systems together, a UART.