For time and money value the Husqvarna 323L brush cutter / trimmer that I bought (2006) has been invaluable to me. I have probably 150 - 180 hrs / year on that machine alone. It is a straight shaft unit that I bought with a 3 prong blade, a circular blade, and the original string attachment, I also bought chaps and faceguard/ earmuffs. I get a real kick out of using it, and it keeps the weeds back and the property looking nice. With a sharp blade I can cut down sapplings up to 3 inches diameter - that takes care of a lot of new growth that is basically in the wrong place (the stihl chainsaw takes the larger items). I think that I have had the blades on it for all but 1-2 hours of use. I live in the country, and manicuring the property with the string trimmer is not often necessary. I replace the blade every year or so.
(my only complaint with this machine is that for a left hander like me, the muffler /exhaust is located in the area where might right forearm rests - as a result, after several hours of use, I might notice some engine burn marks on might right forearm. I discovered this problem after about a week, so I wear a long sleeve shirt now)
When my wife wanted to use the string trimmer on occasion (requiring switching over the attachments), I decided that a second string trimmer was required. I went to town and bought the Echo GT225 trimmer - adding the triple plasic prongs in addition to the string. It is great for the light duty stuff and I don't have to switch anything over.