I have Field and Service grade Garands in Springfield and H&R, and once you get them home, stripped, cleaned, inspected and lubed correctly they shoot just the same. I'm a shooter more than a collector so I really can't speak as to which would be a better value or hold that value better. I do know Winchester mfg. Garands command a pretty penny (if you can find one). Some folks like the early serial numbered receiver specimens, and if you can find a low numbered one with matching mfg. parts I'd count that as a win. Since I like to shoot them, I look for low muzzle erosion (M.E.) and throat erosion (T.E.) numbers denoting less use or more recent rebuild status.
A CMP F.G. or S.G. Garand is an excellent value for what they charge. They make great restoration projects if you are so inclined or you can leave them as purchased. I know mine are great shooters.