I don't think there is an answer to that, because even strains with less THC can produce a stronger high and visa versa. Each strain has unique qualities that make up the high and there are so many I think it would be all personal preference. Because I know personally, I say all the time "Damn this is probably the strongest strain I've had this month" then next week my dealer will have 3-4 more strains and there I go saying it again .
A minute on google tells me that somebody was busted with some Warlock that had a 29% THC percent, but that isn't the normal amount for that strain. But there are lots of strains that range from 19-24% which I think is the highest that would be obtainable and even then under optimal conditions. You can get Rocklock (warlock x rockstar) from attitude seed bank if you are interested in that, although I don't know where you could get just warlock. Kind of pricey though.
I've seen marijuana with up to 25% thx b4. But as mentioned earlier that does not mean best high. A good ratio of thc/cbd will get u whT ur lookin for. Just search. You will find.
I got my last seeds from attitude so I will be using them again!!!! thanks ill check warlock out whats it like to grow is it difficult do you get much buddage and does it smell much more than your usual - cant be too smelly for me as i have family round all the time
Warlock Short flowering, mostly indica but has a head high and sativa traits. You can also get a feminized version. Magus Genetics Warlock Rocklock (warlock x rockstar) Short flowering big yield but this one has more of a body high. You can also get feminized. DNA Genetics RockLock