I know this list is for good sellers, but I do want to mention one that I bought from and that should be avoided at all costs for citrus:
https://www.plantencentrumexotica.be/ (Belgium)
This store is not specialised for citrus, small amount of varieties but the plants come from sicily in heavy clay soil, probably treated with hormones to make them look nicer , they died several weeks after repotting and some of them even had pests (one came with wool lice, other with the armoured scale aphids.
They don't always respond and lie about what they use for soil and how customers should care for citrus plants.
Same with this store (who is looking for a new owner):
https://www.vreeken.nl/ (The Netherlands)
They sold me Kaffir limes that were left in the cold and suffered clear cold damage, I was able to recover them but they're really looking in bad shape. Owner does not respond email and is angry at people when given negative review at trustpilot.
I then went to get plants from Oscar Tintori, they were very good, I did notice difference in use of soil, some plants have loose soil, others have heavier clay soil but nothing as bad as the one I bought from in the beginning.
Tintori's plants have survived me so far and they are very good.