Depends what you enjoy watching. As a Seahawks fan, you value a good team that has won in the past but they make some insane calls (run the ball with Lynch!!!!) and may be on the edge of decline. That basically describes Arsenal.
If you do not want to root for a Manchester team, and good for you, then I'd recommend Liverpool as they have a truly insanely fun to watch squad with a swaggering head coach who only believes in attacking at all costs. Rooting for them will always be fun but you'll definitely develop a heart condition since they are allergic to holding onto leads. Plus, they have a recent habit of losing their best players eventually to Spain.
If you want an inferiority complex, try either Spurs or Everton, who are always playing second fiddle to their "bigger" brothers clubs in their cities. Spurs have more talent but Everton have a manager who can help in placing bets.
Beyond that, root for Huddersfield if you want to make a friend of Patrick Stewart but they may not last beyond this season.
Otherwise, pick any team and just immerse yourself in their history and go from there.
Take care all.





