It's not that simple, you have tangible and intangible. All hosts can provide tangible benefits based on pricing, but it's the intangibles that help drive the revenue. For example Nexcess on certain plans host much higher grade sites than smaller or mass market hosts, that helps areas such as ranking.
It's not all about the performance, under 1s and you lose conversions. Once you go to a host it's not that simple to move, so who do you choose. Rackspace is good if you need fall back support, but you're paying for a service that 95% of the time you will not need, basically Rackspace is a business host. The performance hosts are technical based and if you have business issues you will generally not get any support, such as why an extension is not a good idea or not working correctly.
There are very few that can do both, as most of these are 'enterprise' grade who can balance technology with business, choose which side you want to be on, however with your budget you're looking at the technology hosts. Nexcess is as close as you will get to balanced outside of the services we use, which is an exact balance. The problem is the closer you get to balanced the more you will have to adjust your business model to suit the hosting, as they know better than you how to achieve the results.
