One of the things I love about Community is how painstakingly self-referential they are (reminds me of Arrested Development in this way). So while the first half of the first season isn't stellar, it keeps on building upon itself and rewarding continued viewership and repeat watching of the show with little nuances you don't catch the first time. So by the time you get to season 2 & 3 with all of the concept episodes, you have these wonderful homages to different shows and movies while being layered with these characters you've grown to appreciate.
The Big Bang Theory isn't the pariah it's made out to be, but it is definitely not nearly as well thought out as Community, and doesn't stand out in any discernible way in the sea of sitcoms.