I don't know who is going to decide which are the 5 most important, but here are three:
1. My number one request is simply for you (ASA) to stay here and participate. If you see a discussion about a certain feature request and you've forwarded it on to the proper people, tell us.
If you see a discussion about a certain feature request and you know for some reason it just isn't in the cards anytime soon, tell us if you can. If you know I want a pony for Christmas really bad but you also know it's not going to happen, tell me now - don't let me anticipate it and be disappointed on Christmas morning.
2. More channels, lots more.
3. When I put a URL in the filter, give me a few check boxes or space for text so I can tell you why I placed that URL in my filter. It may be a competitor, it may be an ad that has nothing to do with my site topic, it may be a misleading ad, it may be an ad for an MFA site, etc. I think Google can learn a lot just by knowing why certain advertiser URL's are rejected by publishers.