REAL alaskan thunderfuck was defintely the most potent strain around back in the 90s, but don't imagine you'll ever see it as the breeder only sold bud and never passed any seeds, cuttings or even it's recipe along. matanuska thunderfuck is a totally unrelated strain just like several big buds that are just cashing in on a name
heroana is considered to be "the" most potent strain you can get according to the THC numbers i've seen that go up to or even 30%
AK-47 might not measure with the absolute highest THC level, but there's a reason it's known as "the one hit wonder"
G-13 is a strain bred for potency and famous for it, but like thundurfuck & big bud, what's called G-13 isn't necessarily that from what i've read and there's still much debate about not only it's origins, but whether it ever even actually existed
on the sativa front, i'd say high quality seeds' haze x skunk isn't going to be embarrased by any of the above strains for potency as this one has a potent HIGH where the others are all stoner bud. there might be even more potent haze (or cheese) skunks (or thais) but it's the best indoor buzz i've ever smoked and even more potent than the best i've ever smoked, columbian gold. what it lacks in sensual trippiness, especially visuals & light floating feelings, it makes up for with euphoric motivation and a buzz that lasts hours that you can STILL feel the next day and that eventually starts building in your system. it's a strain you DO NOT want to overdo like most potent IBLs as it will give you the dreaded room spinning effect. to me, THC profile is more important than absolute potency and HxS has BOTH qualities in ample abundance. the most potent buzz is no fun if all it does is put you to sleep. HxS keeps you going and focused. it helped me quit drinking a 6 pack a night cold turkey as well as got me dieting unintentionally at first by just ignoring my hunger pangs, but then by staying on a mostly carbs diet once i realized i was losing weight. there are probably even better IBL leaning strains out there, but i haven't tried them yet and any strain that gets you high and is even more potent than columbian gold is anything but shabby. i'll stand by my naming it as a 100% connoisseur pot snob pleasing strain. i don't know that it has a ceiling either. where eventually i'd go on vacation from smoking gold after a month or so when it's buzz degraded to stony from a tolerance buildup, haze skunk was still building up in my system and leaving me with a 24/7 mild perma buzz after a month. it's worth the 12 or so weeks needed to finish and puts the haze i tried to shame in potency and trippiness if not having it's delicious grapey flavor and having a much less enjoyable cigar wrapper with hints of ashtray flavor. if i didn't know better, i'd swear my landlord dosed the soil with cigar, but maybe it was just a cheese pheno skunk. regardless, once you get past that 1st hit and it starts hitting your system, it's easy to tune out the flavor and i can see blunt lovers actually loving it.
as mentioned, white strains like white widow are bred for the most THC and their showy frosted snow caps, but are notorious for being harsh & not very tasty. those tend to be stony more often than not, but medicine man (aka white rhino) has a trippier profile than the other white (or black) strains i've read about. i bet my white castles would have been potent, but they were also potently stinky, so i cut them down
some other strains to look into are C-13 (not G), hashplants & OG kushes
