There's about ten different things it could be, most already mentioned.
I used to love the evod more than any other vape including the Protank. When I added air flow control to the Protank, and made it draw like the evod, I thought I had found it. Neither compares to a carto tank, NOT A CARTO, a carto tank, properly primed and punched, vaped at the correct coil temperature (Watts/volts). The reason the evod changed from my favorite to NOT MY FAVORITE, is because my taste buds changed. I didn't realize this at first. Suddenly, I could taste the wick a bit more, the heated wick/slight burning of the wick a bit more, etc. Still loved the draw, but too many untasty things now emerged. It was me, not the wonderful evod. I tried re-wicking, turns out I could do that fairly easily after a few attempts. Turns out that cotton tastes better than silica and vapes a bit better, probably due to better saturation. Like you, I pursued the best vape possible, within reason, and not requiring rocket surgery.
My pursuit led me to check out carto tanks. Bingo. Not only a better vape, in every way, VTF (vapor, throat hit, flavor), but they don't leak either. Once you stop dumping the whole tank of juice in your lap (early learning curve issue - and need to be careful - and procedurally accurate), and getting the right tanks and tank tools (Big Daddy's SYM and case, my favorite) and the Siam Mods Carto Punch, not the smoktech, my preference and a big Wow difference. The wife feels the same way. Cartos are a personal preference, and many swear by their favorite brand. I like the Boge's, but I haven't tried Ikenvapes yet (their site is still down), and want to. Usually buy in bulk, five boxes for $25 and free shipping, so a buck a piece, or about the same price as a head coil on the evod, maybe even less (unless re-wicking). IBTanked and Phiniac tanks (love the Phiniac - sandblasted dragon name Puff), and the wife's purple moon fairy. Now my ADV, and rarely use the evods ever now. Occasionally use the PT and Davide's out of the house (convenience). Punch the cartos five in advance (one box), so ready to prime and use without much hastle, and similar to replacement coils. Just a great, great vape, imho. Prefer the standard size and resistance over the XL's and F16's. Won't get into RBA's, but starting my journey there and have four nice pieces so far (but really a different post/thread).
Anyway, my rambling two cents. Good luck, happy hunting, Power up and Vape On!