And to answer OP, look for crosses with strains you've tried and liked.
Some good breeders: Archive, AK Bean Brains, Bodhi, BOG, Cannarado, Capulator, CSI Humboldt, Dungeons Vault, Dominion/Duke Diamond's Vault, Dying Breed, Exotic Genetix, Mean Gene/Freeborn Selections, Homegrown Natural Wonders, Karma, Lucky Dog, Prolific Coast, Red Scare Seed Company, Riot Seed Co, Sin City, SnowHigh, Strayfox Gardenz/Circle Of Blessings, Swamp Boys, Thug Pug, True Canna Genetics.
Some vendors with good genetics: Great Lakes Genetics, @snowhighseeds, Neptune Seed Bank, Seeds Here Now, JBC Seedbank, Breeders Direct Seed Co, The Seed Source, Speakeasy Seed Bank, Oregon Elite Seeds.
Chem (91/D) and TK (Triangle Kush) have already been mentioned. OG crosses are also strong. Headband and the Pure Kushs (Hollywood, Topanga, Suge) are all strong. As for specifics from these breeders, AK Bean Brains' TKNL5Haze and is supposed to be really strong. Bodhi's 88g13hp crosses are as well. CSI Humboldt has already been mentioned, but he also has good Urkel and Mendo Purps crosses on top of the TK stuff. Cap, DVG, Dominion, Lucky Dog, and Strayfox, Swamp Boys all have lots of Chem or TK crosses. Circle of Blessings is Strayfox's fundraising company. These sell out quickly and all profits go directly to the round-clock care and medical bills of Stray's daughter. Everything from Mean Gene is strong, a lot of his stuff is OG and PK crosses, selected for resistance and outdoor performance.