>>10427428Quan Guan and Sluban are on the upper tier of quality for price in my experience. There have been a couple occasions where I've had a missing or deformed piece but I tend to have suitable workarounds in each case - pretty sure the seller would honor a part replacement request, just never bothered with it. I find Sluban can have fragility issues with connections that even Lego might struggle with a bit which can be frustrating at times, but worth it for the final product.
I will always go with AliExpress Standard Shipping which you can often get free (or the store is offering the desired set at a lower price than elsewhere but charges for the shipping bringing total cost to about the same, no clue why some stores do this but shipping in China is heavily subsidized, to my understanding). Benefit of AliExpress Standard is you get tracking and a reasonable shipping time of two-three weeks, whereas cheaper/lower options can take a month or more. Some places offer a DHL option which will be fast but also crazy expensive.