Top Ten Reviews lists the Craftsman Weedwacker model 41ADZ46C799 as the best grass trimmer as of 2015. This model possesses an effective four-cycle motor and several useful attachments.
Next on the list of quality grass trimmers by Top Ten Reviews is the Husqvarna 128DJx, which is simple to use and has a good power-to-weight ratio. This site provides an overall ranking for the top trimmers, and also details, results for design, accessories and help and support criteria.
Best Reviews provides a ranking of the top five grass string trimmers as of February 2015, according to expert review results. This site lists Black and Decker LST136W as the best, based upon strong performance and effective balance during use.