Vapor Shark 0 Nicotine

I've gone from a 0.56ohm to a 0.14ohm coil in my RDA. It performs well at high wattage, but doesn't hit as well at lower wattages now. Is this normal?

Not only is it normal, it is expected. As you lower the electrical resistance of your coil (build lower-ohm coils), you will be able to increase the power of your device. If you don't want to run higher wattage, I recommend going back to a higher-ohm build in your RDA. The general rule-of-thumb is, the lower the Ohm, the higher the Wattage. For example, if I'm running a 0.5ohm coil in a sub-ohm tank, I'm only going to push 40-50 watts on my mod. Anything higher than that, and I'll torch the coil. However, if I'm running a 0.15ohm coil in a tank (like I am right now), I'll pump up the wattage to 100-120, because the coil can handle the power. One of the biggest issues you'll have if you're trying to vape a super-low ohm coil on a lower wattage is flooding, at least in a tank. In that situation, the wick will actually draw & absorb more eliquid than the coil is able to burn off, because it's not getting hot enough. Conversely, if you run a high ohm build on a high wattage, you're likely to run into dry-hits, where you burn off the eliquid faster than the wick can reabsorb. For the purposes of your RDA, running 0.14ohm at 40 watts is going to give very weak cloud & flavor production, not to mention the possibility of drawing excess eliquid up through the drip tip. Again, if you're not wanting to crank your mod up that high, then you're going to need to increase the resistance of your coil to generate a comparable hit. Thanks for asking for my answer! I really appreciate it, and hope this clears up the confusion you were having.

What are the best brands of electronic cigarettes?

Edit : completely revamping my answer after a year experience trying everything.1)   Forget all cigarette-sized contraptions available at convenience stores and mall kiosks.    They are expensive, fragile, and don't deliver good vapor.2)   A good starter e-cig, which is fool-proof to operate and inexpensive is this the Smoktek Dual Mega-Coil Cartomizer.   You can pick a complete kit online for $50 from any number of stores.3)  If you want maximum vapor production and indestructible build quality, I personally use this bad boy:   It's a Provari power supply attached to a Vivi Nova Mini Tank.   This costs about $180 and is for the truly dedicated vaper.There are lots of people who post youtube reviews of various setups.   The most popular is Pete Busardo.   He's very informative (and often quite funny.)PBusardo's Vaping ReviewsIf you're curious about any product, do a youtube search on the product name and 'pbusardo' and he's probably posted a review of it.As for the 'juice' (nicotine and flavoring you add to any setup), that's just too much a matter of personal preference for me to make any recommendations.   However, do make sure that it contains USP food-grade propylene glycol and vegetable glycerin.   You don't want to be inhaling stuff that's been sloshing inside a rusty bucket for 6 months.   Avoid products from China as their regulatory practices are unreliable.Good luck getting off tobacco!   (If you don't smoke - don't touch these products!)

Can I use any atomizer with any e-cig?

I'm not sure if your asking about an Atomizer or an actual Tank itself. An Atomizer actually fits inside of a tank. The Atomizer is what turns your e-liquid into vapor. The Atomizer heats up the e-liquid producing Vapor. Every Atomizer is different, as some heat to higher temperature. Therefore producing more vapor. But with higher heat you also lose some of the flavor. Not everyone enjoys higher heat as the vapor temperature is also hotter when you draw into the lungs. Every Tank has a proprietary Atomizer, in other words you must use an Atomizer made specifically for the tank you have. Atomizers will have a number imprinted on them. Called an ohm. The lower the number, the hotter the Atomizer gets. Tanks vary greatly. That's a whole other conversation. Hope this helps.