Have heard that one thing to be careful with aftermarket air struts is EDC (if applicable to your car). Have heard of units that have 'fake' EDC units which are not much more than welded on cylinders where the EDC section should go. Additionally, some aftermarket units are "refurbished" (air bag and shock absorber) some are just used parts with only the air bag section refurbed.
I was told of the EDC issue by Air Dominance, who don't seem to be in business anymore. Not a total surprise given communication was very bad the last time I purchased from them, sadly. Still, am very happy with the set they provided for my CLS55 which were totally refurbished (strut and bag) OEM units.
A quick search on Ali Express will give you all the suppliers for the 'new' ones made in China, together with pictures of what they look like.