Between the two of them, I would pick Marvel.
When I was a small child, I loved Marvel. My uncle had a large collection, all reprints, of the original Lee/Kirby Fantastic Four and Lee/Dikto Spiderman. I enjoyed reading those old comics all throughout elementary school. In middle school I became interested in DC because they were doing new things. They had a new Green Lantern, a new Superboy and so on. I stayed with DC for long time until I stopped reading comics entirely. Now I read primarily independent comics and Marvel.
I read Marvel now because I have a greater affinity for the classic Marvel characters than the DC ones. They have Hal instead of Kyle, and Superboy is very far removed from the character I liked as a kid, so I have no interest in reading any of their comics.
Spiderman is part of the Avengers?? Must've happened LOOONG after I stopped reading them. In my day, Spidey would've sooner preferred choking on a ham sammitch before joining some group.
Spiderman is on TWO Avengers teams and the Fantastic Four. It is ridiculous.
I like the current FF run, but adding Spidey to the team just comes off as stupid to me.