I don't think there is a scientific answer and I think it is totally subjective. Do you mean like most psychedelic? Hardest couch lock? Best painkiller?
Not trying to be a dick. Just pointing out it isn't as easy as THC. For what it's worth, the strain I am most interested in right now re: power I consider desirable is this Malawi landrace and Golden Tiger:
https://blog.seedsman.com/seedsman-bestsellers-malawi-ace-seeds/ gives you some info. I am planning to try growing both early next year once I have a couple grows under my belt.
The most messed up I have ever personally been (from just weed) that I can remember was off LA Confidential. But tbh I was in college and, while fairly seasoned, less seasoned than I am now. So idk. The best high I have had lately was off some Sour Diesel dispensary weed but I'd hardly call that the strongest stuff ever. The next highest I got lately was from a Blueberry Skunk hybrid that tested at like 18% but had me more stoned than most stuff over 22%. So idk.