Sensi Seeds most likely has the best Northern Lights seeds, Nirvana's strain is actually called "Northern Light" (without the "s")... not much of a difference but if you check around/do some searches you'll find some who say that the strain was called Northern Light originally. Northern Lights #1-9 are mostly hybrids of other notorious strains. Nirvana claims to have selectively inbred their Northern Light for over 25 years; they have been around for a very long time, so it is possible. I can also vouch for their version, I grew one last year and used it purely as a mother plant to produce outdoor clones... it clones easy (and VERY fast, some root in around 3-4 days!), flowers around 9 weeks (just like Nirvana claims) and is actually some very potent stuff. I have grown strains from many breeders, I usually stick with Serious seeds, Reserva Privada and other high-grade breeders but I have grown many strains form Nirvana as well (AK48, Northern Light, Aurora Indica, etc.) and I was quite impressed... especially for the price. Every strain I grew from Nirvana was fire and they're decent all-rounders (decent yield, size, structure, node spacing, etc.)... bringing me to the conclusion that the people who knock on Nirvana all the time just because they offer better prices are most likely just mad because they can not grow as good as they would like to. Nirvana strains can be just as good as any others. (The same goes for the other cheaper brands like G13 Labs and Greenhouse Seed Co. ...I've grown some nice buds from every one of em.)