Which weed wacker should I get?

I've got the shoulder harness and double handled cross bar. I like that far more then just hand holding the unit. With it balanced as the instructions describe, it's very easy to control, even when walking along the creeks and such.

I've been using the plastic cutter teeth head a lot, but I've switched to a heavy square string. The plastic teeth do cut brushy weeds and such better then the string, but they also cut through wire fence which is annoying when you're trimming near the electric fence or the chicken coop.

I've got several different brush saw blades, none of which have impressed me all that much. From circular saw design to things that look like airplane propellers. None of them cut all that well.

On a cool factor, these units all sound like dirt bikes, not weed wackers. That's pretty nifty.

The units are very solid and reliable. They are also one of the few two stroke tools that will start again next spring without requiring me to tear down and clean the carburetor (someday, I actually will put stay-bil in the gas before putting toys away for winter).

The 80/85 is far lighter on gas then the bigger one is. Neither are as gentle on gas as the toy weed wackers are.

The FS80 and FS85 may be overkill for you, they are pretty heavy machines. I haven't tried any of the attachments, although the chainsaw head looks like it would be good for pruning branches that aren't too high up. The attachments are pretty expensive, and look like a lot of aggravation to change out.

Whatever trimmer you get, make sure it has a solid drive shaft. A lot of the cheaper straight-shaft trimmers still use a flexible shaft.

As bbott mentioned, most of the commercial landscapers seem to use the Shindaiwa cutters.

Some of the professional landscapers around here like the Shindawas as a less expensive alternative...