The Buzz Pro II and Buzz Pro Lightning are new devices, just adding some larger vent slots to the existing Buzz Pro to comply with a new ECF specification for tube mods (the spec doesn't notionally apply until June, but notcigs responded quickly). The tubes are supposed to be getting machined this week, so I'd expect to see them available for sale next week or the week after? Personally I'm entirely comfortable with the existing Buzz Pro, which has three smaller vent holes and a plastic bottom cap that would come off in an over-pressure event (the same bottom cap can be used with original generation Buzz PV).
Infinity Pro is a slightly slimmer, longer, PV, same circuit as the Buzz Pro, just a different battery size. It likewise has the three vent holes and delrin plastic end cap. The
batteries on it are protected, and notcigs isn't secretive about the source. A 14430 3.7V protected battery is not non-standard, multiple sources carry them.
No opinion on the Provari family, though from everything I've heard they are well-built, high performance, products, as are the notcigs PVs. The Provari will work throughout a wider voltage range, although the notcigs family will allow higher watts delivered. The notcigs products provide very solid runtime; the basic Provari has to be outfitted with extender and larger 18650 battery to get to the same approximate time. The Provari are physically heavier, though it is not as if they are a chunk of lead.
I prefer notcigs designs for their simplicity, ease of use, just a thumbwheel to adjust voltage and the firing button. That the notcigs products tend to be lower cost and well known for their ruggedness are pluses, icing on the cake. Notcigs being the first vendor to come up with products meeting the new ECF spec is indicative of their having had a good design all along, a relatively simple update for them, although there's no reason to doubt that Provape wil come up with something soon (if they haven't already).
You might post the same question in the Provari area, to get Provari user inputs. I agree with Str8 that it would allow you to get thoughts from people who are active users of those products, a good thing. I have friends who use and enjoy the Provaris, I just happen to prefer the notcigs products. Either product line will get you to a really good PV.