I asked a similar question last year and didn't put enough details in and the advice was to credit with AA and I dont think that is the best option.

I have a few BA paid business class flights each year, I think last year it was about 25k miles flown. Some of these are US-LHR (which dont credit to AA) and I dont fly AA at all. So last year I didnt get any status on AA as a result of BA flights alone (because I didnt get the minimum 4 segments on AA) and I didnt realize the US-LHR flights do not accrue anything on AA.

I am about to take my first BA flight this week and wanted to see what people would suggest, again I expect about 25k miles or slightly more on them this year:

credit to BA- probably enough to get silver tier status, plus combined with one of their credit cards I can get enough miles to do something with

credit to AS- no EQMs but 125% miles, better than nothing

Any other options that would make sense?