I think that AQA Human Bio (A) is probably the one with the most actual Biology.
AQA Human Biology (A) has lots on microbiology, but it replaces Biotech. stuff. It still has C/W. And it does cover photosynthesis. Stuff about homeostasis is not in Human Bio, but includes a lot of neuroscience that normal Bio doesn't have.
OCR Human Bio is more in-depth about specific Human stuff, but has no photosynthesis, nothing about plant transport systems, barely enough about microbiology, little about ecological cycles, and little about evolution; and it has a peculiar approach to coursework.
Edexcel Human Bio is mid-way between these two - no plant transport, no photosynthesis, but quite a bit about ecology and a specialist bit on human evolution.