I've done both the snake on a kettle and have multiple WSM's.
Infrequently, the snake works fine. I've done ribs, butts, and small packers on my 26" with a snake and they have turned out great. I find there is a little more "fiddling" to dial temps in on a kettle.
I love smoking on the WSM. It's as close to "set it...forget it" temps as you can get manually. You'll get an occasional spike, but not having to "chase the snake" on a WSM (as you would with a kettle with a packer brisket) is a lifesaver.
Long story short, I love "smoking" on my smokers and "grilling" on my grills.