Noob here. I only have a two outdoor grows and one indoor grow under my belt. I've covered eight strains in those grows. I'm a sucker for good marketing and am too easily tempted to try something based off of a good description or review, lol. Hence, I've had eight strains mixed in across those grows. I'm at a point where growing anything is a good learning experience.
I'm sure you know these two sources are regularly recommended by members on here:
B2ACG and
Captain Redbeard Seeds. I believe both have supported this forum. I'm not qualified to speak to breeder quality, but purchasing once each from both of these vendors have been positive experiences. I'll definitely purchase again from both of these vendors with no hesitation.
As far as breeders and new offerings, I'm intrigued by Titan at Robin Hood Seeds. A buddy giving me seedling he started from a Robin Hood freebie (Butter Wavez) is what started me down the growing path. It has held up as the favorite of what I've grown, so far. I think Titan is also tied to Square One Genetics. I'm pretty sure that Robin Hood Seeds is sort of Titan's playground for pumping out interesting crosses. This might go against every rule about due diligence and proofing measures, but he has a loyal following. There are a few vendors that carry his drops and a lot of them sell out in a day or two.
Black Dog Seed Reserve is one of them.
Take all of the above with a grain of salt. I don't have any proven insight to share. Just some stuff I'm eyeballing as I find my own way. If you are on Discord,
Titan's Corner is the server where Titan gives notice of pending seed drops. There's a bunch of people on there who share their grows. For all I know, this is a horrible recommendation. I only know that Butter Waves was a popular grow amongst people I share with. If it hadn't been a freebie, I would have already purchased more seeds. I even communicated with Titan hoping to find he had some he'd part with, lol.
I plan to run seeds I've purchased to learn and develop my growing style/methods. Right now, I think my lean for future seed purchases will involve landrace varieties. I do want to explore some known indica leaning hybrids, but that's mainly a search for a solid strain for sleepy time edibles for myself and interest regular-use interest of a family member. I may also try a Robin Hood hybrid, or two, to satisfy my curiosity, but I'm not solid on that. Some strains from
Mass Medical Strains has sparked similar curiosity. I'll probably make the same wrong turns dozens of times before landing on the right path. for me

.
Good luck with your search. I hope someone here points you to precisely what you're looking for.