We have a few dedicated servers with hostgator and recommend our clients to get shared accounts with hostgator as well.. they have been great for us, fast support and virtually no downtime the last 15 months.
I've only used Hostgator's shared hosting from the hosts you mentioned. Back a while ago I used Pingdom to monitor (for a year) an account I had there, and uptime was slightly above the 99.9% level, if my memory serves me right. Recent experience is quite similar, and I'm monitoring 2 accounts there. Server performance is quite impressive too, as far as I can see.
Now, whether the story is similar on their reseller accounts or not, I cannot tell you.