morally obligated to pick a team to which you have ties of some sort, and stick with it. Ties can be family, mission, ancestry, and so on, or even a collegiate star from your alma mater.

But if you have no ties of any kind to any team (which seems unlikely), then you may pick any team you choose, as long as you stick with it, except for the following:

Patriots
Steelers
Cowboys
Yankees
Red Sox
Dodgers
Cubs
Lakers
Celtics
Any team Lebron is on
Red Wings
Bruins
Manchester United
Barcelona
Juventus
Real Madrid
Bayern Munich
Liverpool
AC Milan
Brazil national team soccer
Germany national team soccer
Canada national team hockey
US national team basketball

Choosing to become a fan of any of the above teams without any ties to the relevant city or area makes you a repugnant bandwagon fan, by definition. As does switching teams when “your” team happens to be good/bad.