My wife and I started out with "tobacco" flavors (Greensmoke cigarette "lookalikes"...blech!) After a while we both gravitated to the "fruitlike" flavors, Apple Pie, Honeysuckle, etc.
We both found ourselves, though, gravitating toward the "lighter" flavors, and I recently bought some "unflavored" in 24 mg. 24mg is a bit on the strong side, so I'm cutting it to 20mg (just add the appropriate amount of VG).
As Super_X noted above, the unflavored does seem to be easier on Attys (the darker juices seem to gum them up faster).
And thinking back to smoking, it was never the "taste" I was after, it was the nicotine and other additives. Over the 50 years I smoked, I changed brands several times. And inevitably, I'd get used to whatever brand I was smoking, other brands then having a "funny" taste to them. But each time, I adjusted.
So, in a nutshell, I find the unflavored works every bit as well as any flavor, and as also noted, is WAY less expensive.
I have 2 grands (and 2 minis as backups LOL), but I use only 1 (grand) at a time. I generally vape on one for a few weeks until the atty begins to deteriorate, and vapor production begins to drop off (even with fresh batteries). Then I switch to my other grand, pop on a new atty, and I'm good for a couple more weeks. As a side note, the wife is at the same place, and prefers the unflavored as well, so that's 2 more votes for "unflavored".
Of course, virtually ALL reonauts will encourage you to have at least a 2nd REO as backup if you can manage it (and extra springs and batteries and charger). You've come so far with this already, if, for example, someone stole your REO, it would be really hard to wait even the short time it takes Rob to send you a new one.