I think coil building is blown out of proportion. At first I was very intimidated, but after actually building my own I see that it's not so bad. The hardest part is figuring out what gauge to use, how many wraps, and how large of a diameter you will need. I played around with it and built a successful one on my second attempt. Just be careful with your ohms.
If you don't want to build, the aspire nautilus would be a good step up. If you do want to build, I would recommend the kayfun lite plus. That's what I jut got, and I love it! I was scared I wouldnt be able to get it to work right, but all fear subsided once I actually got into building it. Watching youtube videos can be helpful, but I'll be honest....only until I turned off youtube and just went about it on my own combining all the things I've learned, did I have a successful coil. Unless you have the exact mod and exact same atty as what's used in the video, with all other factors being the same, you will NOT get the same results. The videos are more to give you an idea of how to get started, not how to finish. Stupid me, I had discarded several nice microcoils built just like as in the video because they weren't reading on the provari. Yet my ohm meter said they were fine. I realized I wasn't adjusting the voltage down on it to accommodate the resistance in the coil. I was so concerned with everything else I forgot the most important part!
Like you, I had only protanks before the KFL+ so I was in the dark. Just sit down and think of what you really want out of your vape. What is most important? Flavor, amount of vapor, quality of vapor, convenience, etc. Since flavor is not my top priority I went with a rebuildable TANK atty, even though I've still got awesome flavor with the kayfun, it won't be as great as I could achieve with a rebuildable drip atty. I prefer the tank because I vape a lot and physically can't place drops on the wick all day long when I'm out and about. Maybe one day I'll get into RDAs but for now, I'll stick with this. And once I get the Kayfun out of my system, I'll go back and rebuild my protank coils.