I've had both Synvisc and Hyalgan(old name for another drug of the same kind) and they worked very well. And the shots aren't that bad. Really depends on how good your doc is at draining/injecting knees.
These fluids came available just as I was getting ready to have both knees replaced so I was in major pain and I was surprised how well they worked. Kept me comfortable for the 6 months I had to go through PT and have testing done prior to my replacements. Definitely worth trying.
good luck.............Jenny