In short You build your atomizer for quantity of vapor... lower ohms = more potential for vapor = more power to run. Once the vapor is made, it needs to mix with air to both cool and move it. more air = more vapor quantity = less flavor. most people find a good balance that works for them between power, airflow, and ohms. [end of short answer]
Me, I am mainly a tootie puffer, which means I vape a fairly high ohms with a fairly low airflow at low ohms. I do have a mutation X clone, derringer, and tugboat drippers, but for my all day vape, I am currently using a Taifun GT @ 1.5 ohms, or a subtank @ 1.0 ohms (I rebuild the stock heads). When I do want to blow clouds, I put my derringer or mutation X (both built at .2 ohms) on my Sigeli 100 and kick the watts up to around 60. I do have a few mech mods, but I am down to one Sony VTC4, and just ordered a few more so I can start using my mechanical mods more (I refuse to use anything but Sonys in a mech mod).
The Mutation X is a good variable dripper, but it was designed to be a cloudchasing atomizer with flavor chasing secondary. It has good deep wells, four post design on the later versions, and a huge airflow. There have been several versions released, and even more clones made. To get a an idea,
here's listings for Mutation X clones from one place I frequently order from. As you can see, there's a huge variety and versions out there. Some have heat sinks, some have chuff caps, some can barely be called a mutation X. Some even joke about mutation X styled spoons:
In either case, to upgrade from my horrible version, I have my eye on
this one. If I had to offer an alternative dripper, I'd recommend a
Derringer. It is a lot smaller of an air chamber, which gives better flavor, and it has enough airflow to be good. It does get hot though, but it's still a good dripper.
I know I link a lot to Fasttech, but it's my main supplier. They have both good and bad stuff, so buyer beware. Still, they have good prices.