Dedicated hosting is ALWAYS recommended over VPS, as in VPS there always is a layer of hypervisor in between hardware and host, so for example if you have identical hardware resources (4 core, 16GB RAM) on a VPS and Dedicated box, a dedicated server will always be superior in performance.
Also to note, not all hosting providers truly dedicate CPU and RAM resources to their VPS's, its kind of shared, just to give example, if you see Contabo's VPSs, they have clearly mentioned RAM (Dedicated) but with CPU cores nothing is written, so its fair assumption these will be shared.
Where you mentioned setting up RAID on VPS, every VPS comes with RAID Drives setup already on hardware level, or likely they will have connected a SAN to VPS servers, in both cases its always RAID 1+0 protected drives.
But for your work, a pair of VPS's will be sufficient
Also to note, not all hosting providers truly dedicate CPU and RAM resources to their VPS's, its kind of shared, just to give example, if you see Contabo's VPSs, they have clearly mentioned RAM (Dedicated) but with CPU cores nothing is written, so its fair assumption these will be shared.
Where you mentioned setting up RAID on VPS, every VPS comes with RAID Drives setup already on hardware level, or likely they will have connected a SAN to VPS servers, in both cases its always RAID 1+0 protected drives.
But for your work, a pair of VPS's will be sufficient