Definitely choose biology. I do AQA Human Biology at WJEC French at A2 and Human Biology is way less annoying. I can do a unit's worth of notes then I won't have to do any work for it until like 3 or 4 weeks after. You just have to read over your notes and do past papers it's simple. With French, while I'd say it was easy if you're good at it, it's really annoying and you get lots of pointless work and you can never actually do enough "revision" because it's a language