With that much flying, and if in W (World Traveller Plus) I'd be inclined to split my accrual between AA and BA. Here's why:

AA allows you to achieve Executive Platinum (Oneworld Emerald) either by flying 100,000 elite-qualifying miles (1 EQM = 1 butt-in-seat mile) OR by accruing 100,000 elite-qualifying points (EQP). Top economy fare classes, including Y and B, and all World Traveller Plus, business and first class buckets earn 1.5 EQP/Mile, hence it "only" takes 66,667 BIS miles in WT+ (such as your W flights) to get to EXP. That gets you access to first class lounges everywhere, unlimited upgrades on domestic AA flights in the US, and eight one-way SWUs annually on AA metal. Flights in BA WT+ also earn a 10% mileage bonus on top of the 100% bonus on BIS miles that comes to AA Platinum (OW Sapphire) and above, so, for example, if you flew the minimum 66,667 miles in WT+ to accrue AA EXP, you'd also accrue 140,000 spendable AA miles. (Class of service bonuses are 25% for business class and 50% on first class.)

But 66,667 miles allocated to AA leaves a lot of your miles on the table. Depending on the number of segments flown in your travels to NBO, HKG et al, you might very well be able to achieve BA Gold (OW Emerald) in addition to AA EXP. (On BA it would depend on the total number of tier points earned.)

In the course of that, you'd also be accruing quite a lot of BA miles. Without a doubt, one of the best uses of BA miles is for upgrades on BA metal. By buying W fares, your upgrades on BA would be to Club. For example, upgrading to NBO or HKG would require 25,000 Avios, a bargain compared to a straight redemption.

In terms of mileage redemptions, AA is, for the most part, more generous than BA, but there are notable exceptions, particularly in business class redemptions on certain short-haul routes, and also some routes not originating in the UK. But as mentioned, the big difference is BA's inclusion of its punishing fuel surcharges on redemption tickets - often nearly as much as the cost of a basic economy ticket - in addition to the "cost" in Avios. For example, charging US$1000 in fuel fines (YQ) as well as 100,000 Avios for a Club return trip to, say, San Francisco, reduces the value of the points considerably. AA, by comparison, won't charge you the YQ for flights on its own metal, so the 100,000 AA miles you'd use for the same trip are, in essence, way more valuable.

So the upshot would be that having a supply of both AA miles - for straight redemptions, and BA Avios - for MFUs, might be the way to go. Certainly it seems that you'd be flying enough for that to make sense.