I've only had the Pila. I used mine for over 15 months of daily use, and just recently one of the bays stopped charging. I've built up a collection of several mods since I first purchased the Pila, and have about a dozen
batteries in four different sizes, so when I decided to replace it I got both the 6 bay Xtar and 4 bay Nitecore Intellicharger i4. I would love to have 2 or 3 Pila's, as it is a superior charger to the two new ones that I got which I feel are still high quality themselves.
The Pila is a sturdily built charger. With general inspection it just looks like a superior charger in overall build quality. Kinda like the Provari of chargers. It charged my AW IMR's faster than the new chargers do, even when only one battery in a single bay is charged in the multi-bay chargers.
batteries were always charged up to the 4.2 limit consistantly. I once read (and can't find the link now) that the algorhythms the Pila uses can prolong the lifetime of a high quality battery. True? I have the original AW IMR 18650 batteries that I got along with the Pila, still in rotation with about 4 other AW 18650 IMR's that are only a few months old, and I can barely tell them apart from the newer batteries.
I do prefer the spacers that the Pila uses for different size batteries. They allow the batteries to fit better and the batteries are easier to put in and take out of the charging bays. The 6 bay Xtar charger that I have has flimsy wire springs which make installing the batteries in the bays a pain. My 18350 button-top batteries like to pop out of the bay of this charger as the spacers seem to cramp this size. The Nitecore has slider bars that work a little better, but they are stiff and not as easy as the Pila was to use.
I can't speak for or against the top of the line Xtar VP1. It's probably of equal quality as the Pila. You likely won't go wrong with choosing either one.