Hi, I'd like to clarify that we prioritise people who are optimising around positive impact, not earning to give. If someone takes earning to give seriously, then we view that as a good indicator, but we speak to lots of people who aren't considering earning to give careers.

I started writing a response, but decided it would be better to summarise my general thoughts on degree choice and post them on our blog. So see our latest thoughts on how to pick a degree.

Insofar as this particular situation goes, I haven't thought about it much, so take this with a pinch of salt. My gut reaction is that CompSci is slightly more impressive than bio engineering, and if it helps you learn to program better, then the skills will be more generally useful. You also say that bio engineering is a major time sink, which I'd see as a count against it. So, my highly uncertain impression is that I'd prefer CompSci. On the other hand, if you'll find it easier and more motivating to study bio engineering and you'll get better grades, then I'd rate that pretty highly (especially if aiming to continue into research).