Every university in those lists above for graduate jobs has produced notable alumni. So ignore any "lalala has produced THREE more nobel prize winners than gagaga". It has nothing to do with your degree anyway.
As for the whole "exclusive jobs at Imperial over lalala"...this is partly valid in fairness. I know for a fact, that Imperial offers exclusive graduate jobs that no other university does, but this is for engineering. That's because Formula One race teams perform wind-tunnel testing there, and so, engineering students are right in the buzz of it all. Yet again, you'd assume Manchester would have a lot of jobs in journalism/media due to the BBC HQ there. So the key point here is that each has positives. I have no idea about biology unfortunately, but don't be fooled into thinking one university offers all the good jobs. Likewise, don't be fooled into thinking that certain universities do not offer better graduate jobs in their specialized areas than others.
TL;DR - If you're taking it at face value: Imperial.