For versatility, quality and perhaps also price I am totally smitten with my Canon Serenar 50mm f/1.8 (mk 1 all chrome) -- quite heavy and not as compact as some lenses but not that big, now VF blockage, and sharp as a tack, excellent performer wide open too.
I got one for about £40 (it's LTM so you may need a LTM->M adapter.)