If You fly on BA metal / BA ticket, keep on the BAEC. Nothing beats flying in First with the marginal mile spending you appear to need and keep on gaining. Or make the payer of your tickets happy using the WTP and upgrades (at even more marginal cost as long as you know when you are flying).

A more refined rethinking: The BA-flights to BAEC to keep up the gold card and perhaps the needed AY-flights to top up the 800/1500 TP earning (depending on where you live) for the highest OW tier level and maximum miles earnings. And the AY business flights to AY+. Otherwise you would end up loosing the business class mileage earnings more or less. Can you not split your travel between the alliances? With your travel patterns, I could easily support the top tier in three alliances