i got a set of the after market 1 to fit to my car ! they seem to look ok ! and the price wasco cheap not to have i bought them knowing when i fit my anti roll bar my old 1 will prob break ! think i paid about 20 ish pound each i know it was deffo less then 50 for the pair !
I don't think there is an absolute answer to this question.
Some parts will be indistinguishable from OEM and others notably inferior.
It helps if you can look at the two side by side but even that doesn't give you the whole story e.g. material specification.
If your pockets are deep enough than go with the fords ones, lenfordes are a next good aftermarket make, i'm sure i got the right spelling without looking it up for them ones but dont go too cheap with them..my experience with the cheapos.