You didn't mention a price-range, so i'll offer a couple of pricier single coil options in case you're interested in checking them out.
Hurricane Jr: Single coil, lots of airflow for DL vaping. You can close it down quite a bit but I've heard the MTL experience on this tank is poor. I haven't tried an MTL build on this tank because it's not the way I like to vape RTA's. I can tell you that a more DL or restricted DL on this tank produces very nice flavor. Unfortunately, my ADV (fruit/berry flavor) just does not pop in this tank, but dessert/bakery flavors are great. I'm vaping it right now with a simple, spaced 24g kanthal coil at .4 ohms. Great flavor, I keep the power down and get a nice and dense but cool vape. Wicking is easy and if done right, the tank will not leak (as is the case with most RTA's).
Kayfun 5: Lots of info on this one out there, but I can confirm that I personally have never had a single leak/flood/seep from this tank.
I REALLY want to try the Tanko from Odis Collection, this is another single coil DL style tank that's supposed to have great flavor, but I need to cool it on high-priced atty's for a bit. There's not a lot of reviews out thereon this one, but from what I was able to find it seems flavor is standout.
EDIT TO ADD: I just found out about a single coil RTA from Advken called the CP. Couldn't find it at any USA retailers so I ordered it from Heaven's Gifts. I really like their Manta RTA, more than the Reload, so am super-looking forward to getting the CP. Can't recommend it yet obviously but it doesn't hurt to do a little research on it.