The VAMO is pretty good choice overall man. VV, VW, reasonably solid construction etc etc. PBusardo gave it good reviews and there are plenty of others who like the hell out of it and use it on a daily basis.
Probably anything you got aside from a Darwin or Provari or something really top end would be more of a side-grade than an upgrade. The VAMO has all (or more) of the same features as other mods that have VV such as the Lavatubes or the Tesla or things like that.
Unless you might look into the rebuildable atomizers and mechanical mods. Not entirely sure if that's an upgrade depending on what you're after. The changes for a mechanical mod include (often) more solid construction, a simpler design, loss of the vv/vw aspect but the gaining of the ability to use really low resistance atomizers. Some folks like that kind of vape better, I read.