In reply to bouldery bits:
Stronger without a doubt. Being stronger at the same weight carries future advantage if you choose to get lighter. If you get lighter you will be stronger at your new weight, but once you adapt to it you will be weaker on an absolute scale.
Personally I think as long as you have the flexibility to do most ordinary climbing moves, it's not worth spending too much time on. The people I see doing a lot of flexibility work at the climbing wall tend to be very flexible, but not very good climbers.
In summary, getting stronger will improve my (and most people's) climbing more than anything else other than improving technique.