There's a reason that a lot of rebuildable users do all sorts of different builds. I know I have my seasons with different coil types. Sometimes you gotta do a little more than play with different variations of the same build. Different builds with different power needs in different RDA's can evoke different things in different flavors. It's not something to be understated. Your build choice can make all of the difference.
Just keep tinkering until you find a build that makes a juice you like taste like something completely new. I can't tell you what will give you the balance you need to enjoy flavors again. You're going to have to identify what makes a good vape for you and start isolating the parameters of your builds yourself. The number of factors and combinations are many and most are subjective.
In terms of mechanics and bare characteristics, it's easy for me or anyone else to tell you what you can do to get such and such result, but whether or not that'll wind up being to your liking is anybody's guess. Sometimes you just have to take what you know of what you liked in previous builds and put it to use in conceiving of builds that improve upon those or bring something new into the mix.
It's mostly a matter of intuition. It gets easier to find the right builds as you get to know what you really like in a build and come to understand what objective traits get you that result. This stuff can't be taught as easily as build theory can. It's something that we all go through and it's something we all have to get ourselves through. It's disappointing when your favorite configuration no longer does it for you, but that just means you're ready to progress to something better.
Maybe start by getting an assortment of wire gauges. I would recommend adding 24, 26, and maybe even 22 to your collection. Maybe pick up a couple hundred feet of 34 and 36 in case something leads you to try claptons. Limiting yourself to 28g in an RDA is a recipe for disappointment. I cannot stress enough how low of a ceiling you have by using just one type of wire. You can use thicker wires at higher power levels to get more flavor, more vapor, and different palettes of texture to play with. Different gauges have different paradigms and changing them out often has a drastic impact on the overall character of the vape.
Try some twisted builds. Parallels. Twisted Parallels. Claptons. Anything that you haven't done yet. Find a new RDA or RTA that's inexpensive, has appealing features, and gets high praise. As you familiarize yourself with a new device, you may find that your building tendencies change... ...maybe you get some new insights that translate to you doing better builds for atties you're more familiar with.
Little things like this contribute a lot to one's ability to coax a satisfying vape out of a rebuildable device. Be patient and break it all down. Identify as many options as you can and try them all! Take the time to test every little parameter you can think of. Trial and error. Vape and learn.
"Zen and the Art of Coiling" aside. Try twisting that 28g up. Shoot to be in the ballpark of .2-.3. Add another strand to your parallels. Dual triple-parallel 28g at .16-.2 produces warm, lush flavor, though for someone at the point you're at, the kick and heat may be overbearing. It's definitely better suited to something with very wide-open airflow.
Almost forgot about wicking... ...the general rule of thumb is to use as little cotton as you can get away with. You should just barely feel any resistance as you run it through the coil. Also keep it as short as possible. For drippers, you want it just long enough to rest on the deck. This is to facilitate better airflow under, around, and between the coils. For tanks, you want it just long enough to reach the intake, as the shorter it is, the faster the juice gets from the tank to the coil.
Unless you're doing the scottish roll method, keep it fluffy - don't roll it or twist it tight. Baby it. If you're using pads, cut strips along the grain so you have straight channels going through the wick.
EDIT: LOL "Train and error" thanks FF spellcheck. Oh how I wish you had reading comprehension. Then you'd know that's not a thing that anyone would say.