Outwell tents are where it's at for decent quality. Out of a lot of Vango and Outwell tent sales where I used to work, Outwell had BY FAR the lowest number of returns.
Anyway, I'd be looking at 3000 at least. 2000 is OK, but under continual rain 3000 is much more likely to keep the water out. It's alos likely to last more years before it fails.
HOWEVER always remember that in wet conditions, the inside of the tent is MUCH more likely to get condensation as the rain cools the tent fabric down considerably, and you get the single glazing effect – lots of condensation on the inside. Many people mistake this for water leaking through. To avoid, try to keep as much ventilation going as possible and avoid tents where the groundsheet is sewn into the outer fabric, as this prevents air circulating fully between the inner and outer fabrics. a groudsheet sewn into the inner tent is fine.