I've never heard Vega or Ara but I have a lot of experience with Dorado, Andro and Solaris. My answer is basically that it depends on you and what your preferences are-- each of those 3 Campfire IEMs could be recommended for one thing or another. Each IEM in Campfire's present lineup occupies a unique niche on a spectrum from super musical (Vega), skewed towards musical (Dorado), balanced (Solaris), reference with a dash of musicality (Andro) and reference (Ara). If you prioritize the speed, clarity and coherence of a BA setup but also want your heart stirred then Andromeda can be a great option. If you want a bit of that but also some holographic staging and a subtle dynamic weight to the low end then Solaris could be the one. If you want a dominant low end, clarity, super natural timbre and solid technicalities, and don't mind the upper mids being pushed a little behind the bass at times then the Dorado 2020 might be the one. In addition to your general signature leanings the type of jazz you listen to could determine which IEM is best. Stuff like Chesky's Jazz in the New Harmonic or Snarky Puppy would probably be best served by the Solaris. On the other hand if you, like me, like old school Blue Note stuff or stuff like the following that often really benefits from an emphasized bottom end like the Dorado 2020 then that IEM would get my hearty rec. Dorado 2020 is presently my favorite Campfire though I recognize a good deal of personal preference is behind that.
Dorado's low mid/mid-bass emphasis does great justice to something like the following:
IMHO Dorado 2020 has the best lower mid/mid bass response & transition of anything out there right now and if that area is a priority for you (Do you listen to a lot of CCR? Fogerty's husky soulful drawl has never sounded better), and if you don't mind it at the expense of some upper mid/vocal presence then I would consider it a serious option. On the other hand if you're looking for a more speaker-like presentation with more of an emphasis on balance & holographic stage then consider the Solaris. Lastly if you're not really sure and just want something you know will sound great with everything and never fail to make you happy (unless you really need a dynamic low end) then Andromeda 2020 is always an option.