Presuming we're not including international teams (where fairly obviously I'm Welsh first and foremost followed by Irish though I do have a passion for the Italian soccer team - see my first team below for the reason why).
1. Inter (without a shadow of a doubt, even though soccer isn't my favourite sport, they're by far and away the most important team to me.
2. St. Helens (rugby league)
3. Kilkenny (hurling)
4. ASM (rugby union)
5. Celtics (growing on me very quickly).
I know I will be the oddball person here so here goes:
Boston Celtics
Miami Dolphins
Utah Jazz
SF 49'ers
Iowa State Cyclones
Haha! At least yours are all in the same country. See mine - 1. Italian 2. English 3. Irish 4. French 5. American!
I really only watch the basketball and soccer these days. So it's:
Boston Celtics
AS Roma
Chelsea
Orlando Pride
USWNT
I giallorossi? Tanto fumo, niente arrosto!