I use nitrile over vinyl when the occasion cals for them- need to be able to feel small parts. the nitrile are a bit tougher, it seems, but cost 2x as much.

I have a pair of mechanix brand gloves- free w/ a gallon of valvoline- they are pretty nice, but not worth $20, IMO. and only for the ruff and tumble stuff like tires and brakes.

I use many pairs of the $1.50 a pr knit gloves dipped in the blue vinyl. they are great, and priced low enough to toss out after a single dirty job- like soaking up gear oil. but also rugged enough for reuse until worn out. I just git 3 pr today @ northern tool for $.34/ pair. these are my gloves of choice for the scrap yard- tuff enough to take some abuse, but if you drop one and leave it behind, it really doesnt matter.