I usually rent with National but was unable to get a one-day reservation at PHX this week. So I went with Hertz for the miles (2750, no 5000 bonus unfortunately).
I was reminded once again how badly Hertz sucks. The service is terrible, the vehicles are cheap, and they nickel and dime you on everything. I reserved a full size and they tried to give me an intermediate. The Gold area at Sky Harbor had about a dozen people standing around waiting for help and zero employees anywhere to be seen. After rejecting the first two dogs they tried to give me, I wound up with a gutless Chevy Malibu for $66/day. The contrast with National is really stark, especially at PHX, where National has an excellent fleet and I typically get a 2 or 3 class upgrade just for being Emerald Club.
I don't care how many bonus miles they give out, I'm never voluntarily choosing Hertz again.