Want to share my perspective with you since I was in a similar place. Starting vaping about 5 years ago and continued with the vaping progression up until a few years ago. Stopped with a provari and kanger mega.
Recently starting to look to upgrade. Below are the tanks I've tried so far and my thoughts. I also Mtl.
Goblin mini-great flavor, you can Mtl if you limit airflow. Glass drip tip is real ok, tends to get warm. Filling requires you to carry a small screw driver. Have built in it 4 times and my success rate is 50%. Twice no leaking and twice leaking. I'm sure it's user error, but never the less it does not seem forgiving. I plan to use it going forward but too many cons for me to use it everyday.
Ud bellus-not really a Mtl for me. A bit too airy unless you close the airflow all the way down, but it just doesn't seem to be made to vape it that way. Nice tank if you are ok with a restrictive lug hit. Awesome flavor.
Serpent- more Mtl than the bellus for me, but still a bit airy. Keep in mind I'm newer to building but the deck on this one is a pain for me because of the positions of the build posts. I have had no leak issues yet but from what I read it's only a matter of time before I do.
Squape clone-My favorite so far. Mtl for sure. Good flavor/not up to the goblin but good. No leaking. Very easy to build. I'm using the w deck. The only
Downside is filling is a bit more difficult. I have heard it's easier on the authentic. As of now I'm using this daily. I would recc watching pbusardos review on this one. You'll see what I'm referring to about the difficult filling.
I have a clone hurricane and kabuki coming in soon. I'm hoping the hurricane is going beat the squape so I don't have to deal with the squape filling.
Hope this helps. Good luck!