Revisiting this old post...
VPS is not really about power, but control. (Power = more space, more CPU, more RAM, speed, etc.) And if you have the admin skills needed, it can be a good step. Then you're the decider on what the server uses (php versions, MySQL vs MariaDB vs Percone, cache types, CloudLinux limits, etc), and not at the whim of the host. But it all goes back to whether you need the power -- and the HASSLE! -- of admin'ing your iown system. And yes, even when managed, you need to know what do do. Even proactively managed hosts don't really take it upon themselves to optimize your LAMP stack, etc.
Note that a shared/reseller host (hopefully) optimized their servers already. You're just a resident on the box. A new VPS or dedicated has almost zero optimizations. So yes, that means sites on a VPS/dedi can actually run slower than a good shared/reseller account.
Things like OpenVZ vs Virtuozzo (or Xen, KVM, HyperV, etc) also considerations, making a decision more complex. But know that all are generally fine, aside from OpenVZ, which is ancient and not true VM isolation.
You were looking at 3 excellent hosts:
Veerotech,
LiquidWeb,
Knownhost. And, of course, the quality of the host also matters.
The
LiquidWeb/
WiredTree debacle of 2017 is essentially over, and has been for months. The WT hand-off to LW was botched, and LW got the blame for it. Simple as that. It's so sad how many formerly good hosts have crumbled when bought out. Sometimes it's the new host at fault, sometimes the old.