My goal is to keep the balance as small as possible, earn and burn is the name of the game. I view avios ( or any reward points scheme) as a very transitory currency that can be devalued at any time. So I consider them to have essentially zero future value, the question of "what are they worth" is what can I buy with them today?
The joke on the AC forum is points are only good for buying toasters, after the scheme was expanded to various non flight things that could be purchased and considering the very limited flight availability.