If you want strong, there's hundreds of strains to look at depending on what you want to spend, same with huge yield... There are strains now that are crosses of big bud and strong strains, creating larger yielding, stronger strains.
People seem to forget that, although strains like widow and big bud are great, they're also actually getting older now, and there's been some quality breeding done since then... I mean white widow hasn't won a single competition in my country since '96 or '97 I believe. Northern Lights still has great base genetics for breeding, but there are better hybrids to smoke, and big bud does have great yield, but it has been used to increase yield of more potent strains and there's better stuff out there. Big Bud is still great for private breeding purposes tho, I use it myself actually.
How much you looking to spend on your beans anyway?