HP’s servers are the best in the industry, in my opinion. We’ve been using the ProLiant line for 20 years, and it’s a solid workhorse.
I wouldn’t spend a dime on anything from IBM. Their xSeries servers were a maintenance nightmare, and you could not PAY me to deploy a Dell server. They’re good doorstops though.
I’ve worked on them all and while I would rank Dell slightly above HP (at least in the servers of the last few years) the IMB x series was ugly. Which is unfortunate because IBMs power series is simply top notch.