Many of the VAG (Seat, Audi, Skoda and VW) OEM factory fit alloys are made by Ronal and Borbet. I believe BBS also make - or have historically made - OEM alloys for VAG. Brands such as OZ also have a reputation for manufacturing good quality alloys. Mak are worth considering, as some of the alloys they produce use existing OEM wheel bolts and I think will OEM centre caps may fit as well.
I find
www.rimstyle.com is a good site in terms of alloy wheel choice; input details of your car’s make / model / engine size etc, and it’ll show what’s available that’ll fit your car. I’d personally stick to something that is the same - or close to the same - size / offset as your existing alloys to avoid potential fitment/ rubbing issues. The calculator on
www.willtheyfit.com website is a useful tool - input details of your existing and proposed wheel/tyre set up and it’ll calculate the ‘important numbers’ for you.
I‘d personally avoid any cheap unbranded alloys, often described as being ’in the style of‘ some OEM designs of alloys. These unbranded alloys are often cheap Chinese imports, and the quality of construction, structural integrity and quality of finish might be ‘questionable‘. Additionally, they might not have been subjected to stringent safety testing (e.g. TUV, JWL or similar / equivalent certification) that alloys from reputable brands will have been subjected to.
I have a set of 18” RC Design RC32 alloys (TUV certified) in matte ferric iron grey finish manufactured German company Brock;
https://www.brock.de/en/) on my VW as they use my existing wheel bolts (most aftermarket alloys don’) and they’re exactly the same size and spec as the original factory spec alloys (7.5J x 18”, offset ET51, centre bore 57.1), so they bolted straight on without the need for new bolts or spigot rings. I’ve had them on my car for nearly 3.5 years and they’ve stood up very well to the poorly maintained UK roads without sustaining any structural damage. I did have to get one cosmetically repaired when and oncoming lorry strayed onto my side of the road, forcing me into the kerb; grazed a small section of the rim of the wheel - sorted by a smart repair.
Some alloy wheel manufacturer / retailer websites include a configurator so you can see what your preferred wheel choice(s) would look like on your car (do an internet search on ‘alloy wheel configurator’). Here’s a screenshot of my car (VW Polo GTI) with my RC32 alloys from the configurator on Brock.de website;