I don't always get a thought to paper in the clearest way. Where I was going was Bill reaches for his 18.5mm, and perhaps it's not the fact it is a prime, but an as-we-see-the-world lens.
This for me is the main reason I am drawn to my 35mm f1.8 lens when using my d5100 and why when I use my wife's V1 I stick with the 18.5mm f1.8. I love the 'as we see it' perspective. For me it's gives such a natural looking result.
I've never used a longer focal length prime so can't compare to say a 300mm 2.8 lens but I find the focus speed to be faster in the primes I have over the zooms.