Personally, I would choose based on:

1) time and avios required to fly each leg of the Ex EU segment. 1 hour and lowest avios would be ideal, 3 is too far IMO.

2) number of flights to / from LHR/LGW. If there is only one or two flights each day...don't miss it or you are aced. Having several to choose from allows you to decide what time separation between flights when back at LHR / LGW you are comfortable with for that trip / time of year.

3) Weather at the Ex EU airport history. AMS is great but in the Autumn or around Christmas...I wouldn't risk it and would rather fly to another hub.

4) price and hotel convenience.

Just my personal opinion.