I started off with Kanger Protanks. Got a nautilus, full size and the mini and I'll never go back to the Protanks! I do have a mini Protank 3 that I absolutely adore! My Protank 2 and 3 leaked really bad and nothing I did would stop it.
I felt exactly the same way. I finally broke down and tried rebuilding my coil with cotton wick. WOW what a difference, and it wasn't as difficult as I expected. That stopped the leaking. Don't throw them away....really! I finally just picked a day to try re building as a micro coil with cotton wick. Completely different tank. I was ready to throw my Protanks out the window.
I also agree the mini PT never gave me the leaking problems....and my wife primarily uses that tank now. It is as reliable as the day is long. It also saw the benefit of my rebuild with cotton though...and we're happy campers.
If you just do not want to wind coils, then I agree the protank is a leaking hassle. The mini is solid.