Started in July 2008 with a bog-standard generic RN4072 pen.
At the same time I bought a Sedansa supermini, Janty Kissbox Classic and Kissbox Yentl, Njoy pen and RN4081 supermini. Never really got on with any of them except the generic pen.
I was in the flush of gadgetry all through the last half of the year so I bought a 901 around September (they were considered the cat's ... at the time, but I only bought mine because they had black batts with green LEDs - a big deal back then). I also bought some Bling cigars and a bunch of one-time use throwaway cigars from Wayne at Heaven's Gifts. I also threw some cash away on Health stuff (via dealextreme, I think)
My gadget fixation was running down by then and I bought a Screwdriver, which sorta finished it off. I didn't buy any more new (to me) models until the Prodigy came out and I only got that to see what the 5v hooha was all about. I didn't care for it (kept blowing up attys and it was too big in my hand) I ended up buying a stack of 18650s for it and I use it at 3.7v only.
So, here we are. My go-to model is still the generic RN4072 pen, although these days it's a stainless steel model. I like waving it about down the pub, which isn't satisfactory with either of my big battery mods, and the cart size is better than the 901, which is the only other atomiser I use. I really think I'm more addicted to the gestural parts of smoking than to nicotine.
The SD and Prodigy come into their own when I'm away from home for a couple of days. This used to involve carrying all sorts of crap around with me but nowadays I jusr charge up the batt stack and head off happily.
So to answer the OP, I'm still using my original model. The funny thing is it wasn't the first one I ordered. I bagged all the brand-name heroes of the time, but they had huge lead times for delivery. In the interim, I scoffed up a Classic Pen set from Jason at the electronic cigarette company. He turned it around in two days and I was puffing on that baby for at least a week before the other models started showing up.
I haven't been disappointed by the RN4072 since the first one I owned.
Emp