This seems to be a topic that often leads to brand wars. I currently own a Husky and a Stihl, but have used and liked a Jonsered in the past. My advice would be to focus on the features you want (power to weight ratio, HP, bar length, compression release for ease of starting, ease of adjusting chain tension, etc). Don't get a huge saw just because it's macho; you need to be able to handle it safely!
After you settle on the features, talk to the guys at your local shop. I mean a place that sells and services them, not a big box store. Ask what they prefer and why.
Educate yourself first, then choose. A good chainsaw can completely change the way you look at a forest! /forums/images/graemlins/smirk.gif
Pete