Without any research it's IMO impossible to make a valid statement. This paper e.g. comes to the conclusion:
objects smaller than 256K are best stored in a database while objects larger than 1M are best stored in the filesystem. Between 256K and 1M, the read:write ratio and rate of object overwrite or replacement are important factors.
And this applies only to their environment (SQL Server 2005). Anyways, I'd say the advantages of having resources in the DBS (e.g. ACID) would predominate if it wasn't for PHP which simply doesn't support streaming BLOBs since almost a decade (contrary to what the manual says).