Hy gandy, for sure the ego one tank would be the best looking tank on this battery and maybe the less costly. Judging by the reviews I would not get a standard Ego one tank tank right now if flavor is what I'm after(also consistency for that matter). And considering the clr heads are just reaching the market I would wait to see what more experienced people have to say about it. At about $15 plus another $10-12 for the clr heads you are already approaching your budget but if your common sense tells you to go for it, do it. Just like I saw mentioned in a review, it depends from what device you are coming from. Upgrading from smaller clearomizers would for sure be an improvement considering you have a head which is at least intended to allow you to rebuild it. In contrast coming from some of the better performing RTAs the vape experience will for sure decrease because they are what they are. You should watch Pbusardo's review for more insight on this.
I have no purchase experience with none but I suppose a lot of the trending sub-ohm tanks start at around $30 or higher, so maybe they are out of the discussion. Plus I agree with you and with this battery it would be wise to stay above one ohm if you have just the one. Sub-ohm tanks are made for variable wattage and box mods with big battery capacities. Anyway, you didn't say much about the way you vape, I would say the best options are RTA's and I don't know of one at 19mm diameter (maybe somebody else does) and less than 19, there aren't a lot. Not considering clones, the big buddha mini seems to be performing and looks not bad too; but maybe it's a bit over your budget, anyway you can check it out
here. I would advice to also ask in that RTA section too, maybe you'll find more options that way. Also you could wait for a Spheroid or a kayfun mini in the classifieds, sometimes they go for real cheap but not less that $50 I think. And you have the older china tanks from before the sub-ohm craze such as nautilus mini or others from kanger. You also have RDAs as a last resort,which unless the world of vaping changes radically I see no way for drippers to abandon us. Hope some of this helps.