Also,
If your Married or living with someone.
1. Room Size also will determine the speaker or speakers you can get.
2.WAF / FAF
3. As others have stated, finally Budget- Take your time, but buy the Best you can afford. (this will Hopefully stop the upgrade bug)- Good Luck.
4. Room decor- Colors. What speakers will go with your Furniture or Architect Tastes...........