Having grown everything from the ultra finicky autos to full out Indica skunk, defining yield would be hard to do, if you want buds that smell like strawberry lemonade you will have to go with the niche strains, if you define yield as in terms of weight (finished and trimmed colas relative to growing space/expenditure) I would have to go with the true 50/50 hybrid original strains. but if by yield you mean amount of harvestable thc9 relative to growing space/expenditure I would have to go with o ne of the original Afghai hash strains, these strains are very resistant to disease, have n almost supernatural will to survive/prosper, can withstand a wide variety of environmental extremes and produce some of the highest quality kief ive ever seen, and if large colas are your thing, these plants themselves do not get huge, but the colas do and rival the looks and smells and density of any strain.
I grew two colas this year that weighed a combined weight of 3.7 pounds and I'm sure that small potatoes compared to some on here. after trimming wet ( i trim pretty heavily on a wet trim so when dry I only have to trim a small amount off and it minimizes handling them. after drying one weighed 7 ounces and the other weighed in at 5.2 ounces so a combined dried weight of 12.2 ounces, i only weighed them that way as an afterthought as i don't try to grow big colas either. They are not only prone to mold but also way more f pain in the butt to inspect for budworms (which around here is the biggest pest problem we have), so if i have to basically dissect the bud anyway, why gro huge ones/