Be careful X core means nothing reliable, for 99.9% of VPS providers, they are not dedicated nor rated and could be divisible by up to 2000 guests (particularly with OpenVZ provider), at least on Rackspace, AWS, Azure the CPU performance is generally within a specific range (variability due to minor hardware config differences, and noisy neighbours, but appropriately restrained). In addition 99.5% of these providers don't have the sufficient knowledge to run a VPS operation, they purchase a few dedicated servers and copy of SolusVM and WHMCS and hope and pray for the best.
I work for an ISP and can put as many machines in our datacenters as I want (within reason, of course) so I only have a few (small) VPSes nowadays. When I used to have a bunch of them, however, I quickly learned to avoid anything OpenVZ-based like the plague.
This is anecdotal, of course, but OpenVZ "feels" very much inferior and the providers running OpenVZ (more often than not) very much seemed like fly-by-night operations simply trying to squeeze as many VMs as possible onto a physical host without any regard to performance.
