It really depends on how often and how confident you will be able to use it in the next year. I usually try to keep 36k avios in my account for two single trips or 1 trip with a family member. Amex has been doing BA bonus annually for several years now, so there is a good chance the bonus will be back 2020, although nothing is for certain.
These avios (also AA miles) are especially good for late bookings (unlike skypesoes, lol). As the cash price typically are very costly for the dates within next 3 weeks, amount of miles for award booking, when seat is available (which usually is, at least for my routes), typically remains the same.