I'll condense this into a list with my thoughts on each
1. Baker Creek Heirloom seeds- generally ive had mixed luck with these. They also have some issues ethically so depends on your pov there.
2. Seed Savers Exchange: love this place. This is less of a seed store and more of a place for different growers to share and sell their seeds. Lot of cool rare varieties. Def work perusing.
3. Southern Exposure seeds: i dont shop here but ive heard ok things.
4. Botanical Interests: They seem alright. Theyre the guys at Epic Gardening Youtubechannel and they produce good youtube content and if you want to support them it seems like an ok source.
5. University Extension Programs: Mine doesnt sell anything I'm interested in, they used to do fruits and stuff. But now they just do like grains.
6. Specialty plant societies (like here!): Definately great to look at local places and such. I am part of the North American Fruit Explorers and they have a scion exchange program thats great too.
7. Wholesale places Like Johnnys, Stokes seeds: not sure if johnnys is really "wholesale exclusive" but IVe had issues with them. One year i bought lettuce and they gave me marijuana seeds lol. Which Is funny but like. That could be pretty bad.
8. Seed banks and Germoplasms: can be good. Usually dont sell to consumers though. you need to have a license to get it. Many of us may qualify though.
Some other thoughts on seeds ive tried and liked:
Trueleaf seeds: has a bunch of cool asian varieties of things through a seed exchange. Where i got some celtuce and turnips this year.
Urban Farmer: had some good seeds from them, often find them cheaper than baker creek and have a lot of the same varieites.
Territorial seeds is great for northwest and eastgrowers and, they got a lot of cool stuff.
Adaptive Seeds: same deal as above
Row7: have a bunch of really cool plants they sell seeds from. I got their beets and potatoes this year. I really like sweet garleek too but they were sold out by the time i got there...