I would have to agree and say that Apache is more stable for long term use.
However, I use IIS, simply because im lazy and can't be arsed to configure apache. I only use IIS for testing on my laptop so it's far easier to get up and running.
Having said that, I am planning to buy a new desktop over the next year and will probably use that as a web server with IIS (after i've installed a decent firewall first, obviously 😉 )