Both. I love how J and Bob Mould can get that lead and rhythm thing going. I started playing rhythm so I could sing, but too many "widdly-widdly" guitar players were showing up for band auditions. About that time I figured "F-it, I’ll do it myself". It’s kinda weird to play with another guitar player now.
Riffs/songs are the key. Solos can really suck if not given a good/great context. They should be like the exclaimation point.