Protank Mini II's seem to gurgle a lot less then full sized, bottom coiled tanks. At least, they do out of the ones I have. I get much better flavor and vapor out of my iClear 30 b and 16 b, and prefer to use those despite the slight gurgling I get when the liquid is low in them. I love my original iClear 30 as well. Tight draw isn't a problem for me, and the only time it leaked was do to an overly gunked up coil. A soak in alcohol and a dry burn fixed it. Drawback to the top coils though, is that when you have to get to the coil, you loose all that liquid. It's like watching money get washed down the drain.

I'm kind of phasing out my top coils because of that. The iClear 16 tastes great and I love the very warm vape from them, but they seem to leak a lot on me, for various reasons. Granted, I can usually figure it out and fix it, but to do so means I loose liquid.
Carto tanks have been phenominal for me though. I use IBTanked glass carto tanks and Smok prepunched cartos. Taste is better then anything else I've tried to date, and so far they haven't sprung a leak. Also, they don't appear to be the juice guzzlers that all my dual coil tanks seem to be. Drawback is filling the cartos before inserting them into the tank. I've seen the videos of filling the little silicone boot they come in halfway, and then place the carto inside, but the ones I got from IBTanked didn't come with those, so I had to drip the liquid in. It was a PITA, but since a tank seems to last me a while, and I'm supposed to be able to just add more liquid into the tank until the carto tastes bad (should get a couple of refills, no?) it may be worth it. We'll see how long the cartos last.