I'm not sure about "best" but I just got some kanger e-smart 1.3 ml clearomizers (
http://www.vaporkings.com/e-Smart-clearomizers-package-of-5-p/esmart-clearo.htm) in the mail today and so far so good. I have tried them on my 78mm & 102mm halo batteries and it's only very slightly larger in diameter than them. Unfortunately the e liquid flavor seems a tiny bit muted but it's not a deal breaker for me. It's actually barely noticable but worth mentioning either way. It doesn't have any added weird/plastic/undesireable flavor, just doesn't seem as sharp as it did in my origional halo tank. Halo's mini
tanks are decent but they don't have a very good seal between the drip tip and the tank. I find that if I leave them on their sides some liquid travels into places it shouldn't be - then I'm rinsing my mouth out. The e-smart
tanks don't appear to have this issue because the drip tip screws into the top of the tank, onto a (silicone?) seal, so I'm pretty happy about that. Actually I'm really pleased with them. They seem good and solid, are prettier than any others I have and they produce a good amount of vapor.
I also got some "KR808D-1 blank clearomizers - package of 5" (
http://www.vaporkings.com/KR808D-1-blank-clearomizers-package-of-5-p/kr808-clearomizer.htm) which are a little thicker than the g6 batteries as well but they seem to be decent. I can't tell if the flavor is any different with these since the liquid I put in it is new to me too. I don't think I like them quite as much as the e-smarts, mainly because the area that the drip tip pops into can also come out pretty easily. I'm not sure how clear that is... think "plug drip tip into mouth piece, plug mouth piece into tank, screw tank onto battery". It seems like this is to prevent the type of leaking I described in my experience with halo's minis, otherwise I'd probably just plug the drip tip straight into the tank (you know, like a normal tank). These don't screw together and some reviewers claim that they come apart where I've mentioned, making a mess. Other than that concern, which hasn't been an issue for me as of yet, they vape well. Can't complain too much.
I got both of these from vapor kings' website, so if you wanted to give them a shot they're both there at the moment. I can't comment on how long they'll last as I only have had them a couple of hours but they do work. Plus, they're only about $2.50 each, though you have to buy them both in packs of 5.
Wow. That's a lot of text for only two suggestions. Oh well, hope I helped. Good luck on your search!