To the best of my knowledge, these two shows began airing around about the same time. I expected them both to be good; HIMYM because it had Alyson Hannigan and Jason Segel, both of whom I knew I liked and found funny from other shows, and TBBT because it was about geeks, of which I am one!
The Big Bang Theory continues to me one of my all time favourite shows. From the original premise of two genius scientist geeks living across the hall from a pretty waitress from Nebraska, we now have a whole cast of varied guys and gals, from the geeks and nerds, to the 'normal' and pretty, and everything in between.
On the reverse side, I gave up with How I Met Your Mother at Season 4. I love the comedy, I love the characters, but I just couldn't stand how stretched out the story became! Ted Moseby has now been telling his children the story of how he met their mother for 6 years?! Its becoming silly, in fact, it became silly a couple of seasons ago, and I just can't stand it anymore!
If and when we ever find out who these kids mother really is, somebody let me know. In the meantime, I'll be watching Penny wind-up Leonard and Sheldon over their geekiness, and laughing like a drain about it! ;)