e.g. if my niche was american football teams i could either build a site for each team or build a site like usafootball . net and just add a section for each team.

what would be the best ?

I would think one site with multiple pages that way with so many visitors for each team your rankings would be better for the one site.

Just a suggestion
Regards
Suave

thanks thats what i thought

I think it depends on where you are sending them to. What is your goal? Are you selling merchandise?

adsense only, it will be an information site

Gotcha. In that case I definitely agree with Suave.

One single would be easy to maintain & update. Also, Low domain costs and hosting costs per year.

I agree with suave.

I agree, if the common thematic is the same, one site with multiple team pages is the way to go.