The Dreamcast worries me the most, it's a regularly used machine for me and I have genuinel lost count of how many have died on my now.
My MegaCD experience appears to be the opposite of most peoples, I find my MegaCD1 to be very robust and reliable, where as I have a box full of dead MCD2's :(
I don't think cart based consoles are anything to worry about for a very long time, my original Atari VCS is still functioning perfectly after almost 30 years.

