There is no list of strongest strains, i mean, you can make a list of best genetics, but it's all up to the grower. Say the strongest strain was 35% THC, that's in the genetics. But if it's grown badly, it could come out to only 15% THC.

So how it was grown is a major major factor.

If you've smoked 4 times you got no tolrance. Try 4 years all day everyday.

Northernlights is one of my fav smokes, i love it, i grow it and i smoke a damn lot of it. I think you just got fucked on some good weed. Be happy.