I've seen no indication or even a murmur that one is more reliable than the other. That doesn't mean it's impossible, just that it's unlikely given that the MR forums are very prone to receiving loud shouts whenever someone has a problem with an Apple product.
Maybe you just had a particular run of bad luck by getting 2 bum ipods in a row, or maybe there's something wrong with your setup that's causing your ipods to fail. For instance maybe your usb port is slightly messed up and sending occasional surges of electricity to devices connected to that usb port, or whatever.