mojohost - had to deal with them for a client once. huge ego heads (i cant believe they won an award). if u are an admin they will drive u nuts. if u need 100% tech support (ie dont know shit about running servers) then they are good for you and priced accordingly.
natnet - worked with them because of nats on
mattsmoney.com. they know their shit.
cari - is great if u are a server admin. clean good CHEAP servers on a fast network. i manage over 40 servers with them.
planet - i have some smooth running servers with them. havent even had to log into those servers in almost a year. high price tho. not sure about support. i think u need to twist those mother fuckers a little if they are raping you. have some balls about it.
everybody else on the list - never tried, but i open new servers every month ;)