The very first thing I look for in a PV now is a High Quality atty connector. Cheap connectors have caused me much frustration with too easily worn out threads and insulators failing prematurely. I'll never buy another PV with a generic/el-cheapo connector.
Over the last year, the feature "feeder" has become very important to me. I have a few bottom feeders and a top feeder. I own several tube mods and I'm aware of the surge tank, but the feature "feeder" otherwise pushes my preference to a box form factor.
Build material: My work and play are rough. Any PV that's going to leave my house needs to be exceptionally durable. So, most of my PVs are metal.
On/Off switch or button lock. I prefer to have a way to shut my mods off. Not all of my PVs have such a feature, but I wish they all did.
Long vape time between charges has also become important to me. I don't really like to carry a bunch of supplies (including extra batteries) with me during the day. I've gotten really spoiled being able to leave the house for 12-15 hours carrying nothing but one device - no extra batts, no bottles of juice, no cartos, nada. Having just one thing and knowing it has enough juice and enough battery on board to go all day offers a lot of freedom.
Three of my feeders are thumb-fire. One of those can also be easily fired index finger depending on which way it is facing. One of my feeders is a ring-finger fire. The next one I'm planning to buy will fire either thumb or index finger depending on which way it is held. I have tube mods that fire index, thumb, or pinky. I guess I don't really have any serious preference as to which digit is necessary to make the device fire.
I have no need of any sort of digital read out. All of my current VV devices have a thumb wheel. One of those thumb wheels came color coded and I color coded another one when I got it. That's enough visual indication for me.
At the bottom of my preferred list of features is regulated voltage and variable regulated voltage. I like having it, but not even 1/3 of my PVs are regulated. -- It's growing on me though. My two most-used PVs are both VV feeders, and my most-used tube mod is 5.0v regulated.
The perfect set of features is a little hard to nail down. I like a lot of different things. I don't think I can really say that one single device could have everything I want or need. On any given day, I'm likely to use half a dozen different PVs. There are reasons for that, and it's slightly more complex than changing flavors... but does come down to the fact that I enjoy a lot of different juices. Some of them I like in this or that atty and some of them I like in this or that carto. Some of them are better at HV, some of them are better at standard voltage with LR... etc etc etc. So, that leads to my having several "perfect set ups" that hardly resemble one another.
