Though there are too many tanks with pre-made coils out there to try them all, I've tried many. Cleito wins for me hands down. I have two and have run lots of juice through them and the only time I've had an issue was 50/50 liquid can spit. I haven't tried less PG than that, but I've had 70, 80 ,90 and Max VG in them. The only time it leaked on me was when I shot juice in really fast with a unicorn bottle once. I knew it would be an issue as soon as it happened.
Flavor is the reason I use it, but the size and ease of filling & cleaning definitely helps. I'm always on a quest though so just in the past two weeks I bought a ceramic COV Defiant tank and a Cubis. Both of those taste muted compared to the Clieto though - the Cubis does have a few things going for it though and one is battery life. The .5 Cubis tastes almost identical to the .5 Defiant, though a little less muted, but that's when running the Cubis at 28 watts compared to the Defiant at 48. I run the .4 Cleito at 38 watts and it runs circles around both of them in flavor and vapor production.