Ask HN: Good VPS for CPU?

Most of the VPS plans out there are a little obscure about the CPU. Heck, I've been owning VPS'es for years and I still don't know exactly how much CPU I got on they. So here is the thing, right now there is this Rails app that we are building and I'm still deciding between using a PaaS like Heroku or get my hands dirty with a VPS. And I'm concerned on the CPU that it might requires. With bandwidth, RAM and disk is pretty much understandable what I am getting (if the provider isn't clear about it you can easy find some reports out there from benchmark lovers). But I have no idea on how to compare CPUs on VPS'es. Anyone personally recommends a VPS provider with a good CPU? Any tips on how to compare VPS CPUs? P.S.: Before you say, I know, getting a dedicated server would pretty much solve it. But, for now, that is way out of our (tiny) budget.