I have a Yoder YS 640.....and wil have another pellet grill here within a month (shhh...
)
My reason for selecting the Yoder is more specific. You question is about pellet grills in general, but - they do not all do BOTH low and slow smoking AND high temp. grilling. The Yoder does, and I know the Memphis and Mak do as well.
So - I wanted something that would cover the spectrum of cooking temps in one unit, provide a reasonable smoke profile, and be as hands off for long cooks as possible - and give me consistent, repeatable results.