I think any feeder is a great feeder
But one of my most frequent fantasies is starting a relationship with a feeder who is significantly fatter than me -- enough fatter that their size interferes with their daily life notably more than mine does (distance they can walk, where they can fit, where they can shop, etc). Our goal starts off with making me as fat as they are, but by the time I'm getting there, there is no stopping and I become notably fatter and become the more limited one. So I guess I'd say my ideal is a fatter feeder who isn't stuck on the idea of staying as the fatter one.