AMPAS or BAFTA: Which is more biased?

BAFTA, full stop.

BAFTA

I'm mean it's hard to accuse AMPAS of this, as the pool of films they are voting from is predominantly made in America, so it just happens. They actually nominate and give wins to a noteworthy amount of people not from US, probably most notably British people. They might have their problems at AMPAS, many of them in fact, but I don't think this specific bias is one of them.

The Brits will flat-out ignore performances dealing with certain fringes of American society (most notably the South). There is no real reason they would've ignored Sandra Bullock in 2009, Melissa Leo's sweep in 2010, or McConaughey/Leto in 2013, or half a dozen other examples off the top of my head. You can (unfairly) call out Hunt/Tomei's wins for being the result of American bias (and not, say, the fact that Hunt had one of the two most beloved films out of the nominees that scored three acting nominations including another win, or that Tomei had a plum scene-stealing role in a sizable box-office draw), but at least the Academy will pay lip service to role diversity.

The Oscars. BAFTA has sort of turned into some sort of joke Oscar predictor now, but go back and look at some of their noms and wins as recently as maybe 15 years ago, and certainly before they moved themselves into the pre-Oscar awards season and they're infinitely better/more diverse in terms of what they're giving notice to. The idea that they're biased against British stuff is funny... The Oscars aren't biased against American stuff?

Every academy in every country leans heavily in the favour of their own countries productions, that's the point of them. Half of them don't even have foreign stuff eligible for main awards the way that BAFTA and Oscar do. BAFTA leans British less than Oscar leans American, right? Unless we're going to give in to the idea that the stuff Americans do is genuinely just better, and half the crap they've nominated that BAFTA ignored was well and truly among the best work of the year from around the world.

Of course lines are blurred because there are so many Brits working in America/American stuff made over here by our guys, and the output of actual British cinema that anyone really gets to see is so miniscule, but considering both of these awards bodies consider themselves open to work from around the world in a way things like the Cesar's and Goya's are not, and AMPAS still leans so heavily American (comparatively far more than BAFTA leans British) should answer the question.