Glidecam , been using mine for 6 years no issue , it may sound expensive but its worth every cent of my investment.. Probably the best investment for video cause it can replace simple jib and slider shots..

Flycam , threw it away in 2 weeks. It goes off balance too easily. Example, I remove the camera and lay it on the ground and it can go off balance , but the glidecam doesnt do that.
Other than that, if you want to save abit of money and keep rebalancing it, go for it.