Which university is better-Aston or Brunel in terms of:
1.Liveliness of the place- Aston in Birmingham or Brunel in London
2. Accessibility to markets,shops outside campus
3. Part time jobs
4.Overall Student experience

1-3 is certainly Aston. 
4 will depend on the course, but probably Aston. 

Also Duncan, do you think Aston being in Birmingham can be a big disadvantage in terms of networking? Do you think choosing a Uni based on the city in terms of networking opportunities a better idea?

I don't see why it's a disadvantage. Aston's in the middle of a huge city. Brunel is just over an hour from central London, so is the fastest train from Birmingham to London. Jobs are distributed similarly to the population. It makes no sense to pick a school with worse outcomes over a better one, especially because of any feature that is not relevant to your goals.