1st May - elections for the Mayor of London and the London Assembly

Being convinced that going to the polls is the least you have to do as a citizen or resident in any democratic country, I'll certainly go next week.
However, being reletively new to the city, I don't know too much about the candidates as such which woud leave me with my preference for the Libdems as a party and no good idea whom to give my 2nd - in this case decisive - vote.
Therefore having a discussion about the candidates here might be bebeficial for others as well who are in a similar position and one source of information (besides discussing with friends and trying to follow the newspapers closely).
Who do you think is the best person to make the most of London's opportunities and can tackle its problems (deliberatly in this sequence - I can't stand politicians who talk about dealing with problems only)?