I need a few extra I/O pins so I did some "research" online.
Sparkfun offers PCF8575C breakout board: https://www.sparkfun.com/products/8130
I am comparing their specs (links on their sales pages). It seems MCP230xx has wider operating voltage range and has several interrupt options and higher max I2C bus speed (none really matters to my project). PCF8575C is a 5V chip and has open drain interrupt.
Price-wise it is the opposite. PCF is twice the price of MCP:
I must have omitted something here. So if you have used either or both, which do you recommend me use? I am sensing rotary encoders and buttons. I will end up using 8-bit expander.