Not that I want to list them, but, I have purchased many at the 1-2 quantity. But, once I found the original Lemo, I now have 7 of those. I know they are inconvenient in some ways, but I like the flavor output. They are simple.
I did just order another KF4, SubTank Mini and a Taifun GT-2. Times are changing as to features and convenience so I am starting to check out others. Since my ohm preference is 1.0 - 1.3, I don't need anything overly exotic.
But, in answer to your question, I change flavors about 5 times a day. I have a breakfast tank with a step-up in nic, currently coffee cake, 6 other filled tanks for during the day and I have 2 drippers that I use in the evening. Those use juices that are a step down in nic and I get my top 1-2 flavors in small bottles just for them. In the evening, watching TV or on the patio/porch I tend to chain vape and don't need a lot of nic.
I PIF'd half of my Nauties and Kayfuns so far. I don't use them. I avoid PIFing all in one place.
So...a bunch of RTA/RDAs. I enjoy the tinkering.