How many times can we have this conversation? Heh, I guess answers change every time...
...lately I've been liking 23g kanthal for my standard duals. I like standard duals for my mechs and I just find that 23 gives me that bump up in heat and surface area over 24 without really heating up much slower or requiring that I build to ridiculous power levels like I do with 22. 22 also puts me past what the airflow on all but two of my favorite atties can handle, so all in all, it's a nice compromise between power, ramp-up, and surface-area for those low sub-ohm builds. It just works well in everything I drop it into.
For series mod builds, I like standard claptons with either 38g kanthal D over 28g A1 or 40g D over 24g A1. I've played around with every combination of gauges and types a bunch and that's the balance I like. Which one simply depends on the airflow of the atty. I just find that those particular wires give me really nice, responsive claptons, what with the thin wire and high voltage. The 38/28 lets me build as high as .8, so I get a great, high-power style vape for less, while the 40/24 just lets me vape at the somewhat absurd .45 without turning juice over. At 7 odd volts, they leave you with something that you can take very short drags on and get these huge, warm, dense, textured, and FLAVORFUL clouds. I'm in love with the vape those wires give me.
The kanthal D outer wire is merely a matter of price, btw. A few thousand feet of kanthal D costs way less, but it's essentially the same as A1. Other than having a slightly lower RPF and max temperature, it performs the same, especially for claptons. If I could find it in lower gauges, I'd use it exclusively.
For my high-powered regulated mods, I like to make full use of that power with fused clapton wire. No real preference there, though I tend to stick with 24g or 26g kanthal for the core and 36 or 38 for the outer wire. Sometimes I like to stage them with 28g or 26g kanthal. Nothing too fancy.
So the wires I always keep on-hand are 23g, 24g, 26g, 28g, 36g, 38g (kD,) and 40g (kD.) All kanthal. The sad part is that this is a only a quarter of the variety of wire I have. The majority of it just sits stuffed in drawers unless I'm doing a trick build for somebody. I have the essential even gauges of nichrome, a full assortment of kanthal (even AND odd from 20g to 46g,) some SS, a couple of spools of nickel... ...I dunno, I just always tack on something different when I re-up on the stuff I burn through.