Ok so mainly, your devices are all regulated. 0.3 - 0.5 ohms is where a lot of regulated devices like to shine. Generally what I've found is coils closer to 0.1 ohms get a bit hotter during the vape, but I am a mouth to lung hitter so I need them to heat up fast. As far as 0.3 ohms goes, on a regulated device there's not really a problem with that, or even 0.5 ohms which is a good point for most regulated devices. When building RBA sections for those, the only thing I ever really liked on my regulated devices were the claptons. I haven't had any other build really shine on any of my regulated devices but claptons so... I've tried twisted and just about anything my mind could conceive to put on the regulated, but claptons shine the most. If you're not a clapton type of person, I think that temperature control is really the next best thing, or even better to some peoples standards. The best part about Ni200 is you can make a spaced coil with only 4 and a half wraps and it will vape awesome. RDA, RTA, anything with a build deck can use temperature control, so I would definitely suggest it. But if you haven't tried a clapton yet, definitely check them out.
EDIT: Forgot to say, I like my claptons around 24-26 gauge wrapped with 30 gauge, but you can go higher gauge on the clapton wrap like 32 or 34. It's kind of a preference, 30 gauge will lead to bigger gaps and more surface area than anything smaller (duh) so just use your imagination I guess.