There are only 2-3 great franchise quarterbacks on planet earth. It's an extremely hard position to play well for an entire season, and way harder than that to be consistent. There are only about 4-5 other players that are consistently good. There are 4-5 that people call franchise QBs but it's all based on potential or draft slot or one great season.
This just in, being a real "franchise QB" for a few seasons in a row let alone several doesn't happen all that much. And you need to have very good receivers, a very good line, the ability for your team to run, and very good coaching all at the same time.