70-200 f4 or 70-200 f2.8
The f2.8 is a stop wider and is very fast to focus. It also give you more leeway to use a t.c. if you need to.
The reason to buy the f4 is to save on weight and money. If you don't need to do that I don't see a point in buying it.
|Leaving the office, Central London. by Edward48|
from Your City - Night Shift
|Running free by LassiM|
from My Best Photo of the Week
|Everyone's happy at Disney World! by Pixney|
from Disney World