I own a stohlquist x-tract vest and last summer i wore the astral bouyancy rescue vest for work the whole season. I think both vests get the job done, however there are definite pros and cons to both.
I like the stohlquist because it is compact, has an easy to use tow system, and leaves plenty of room to wear a waist throwbag. However, it doesn't provide much protection to the spine on the upper back and doesn't have a hand warmer pocket to utilize while scouting in the snow.
The astral bouancy has a great fit once you get it on. It has nice features and provides much better protection to the back, with padding coming higher up the spine. It can also be used w/ astral's throwbag (but that is only 50 feet). One huge plus is that in all their new vests, astral has eliminated the use of PVC foam, which has many environmentally harmful and toxic heavy metals associated with its production. Its downsides are the lessened ease of entry from not having it open all the way like a normal vest (uses one connected strap system, this may have changed for 05). And also, it rides pretty low and doesn't allow for a waist trowbag to be worn.
If I was getting a new vest, i would support astral because they are an environmentally friendly business and the design is as good or better than all the others. over and out.