Who knows if any of them could have been good. We'll never know because the Bears failed to develop them.
A team drafting a QB isn't like someone buying a car, and just driving it off the lot and that's now your daily driver car. It's more like buying a Honda Civic, and then having to turn it into a racecar. None of those QBs ever had a chance, because the Chicago Bears are a complete shitshow.
The better question really is, what offensive coach that the Bears have had has proven that he's not a moron for more than one season? Have the Bears ever had a good offensive coordinator? They've had fluke season's where the offense looks good for a bit, but they've never had any sustained success, and every offensive coordinator ends up getting shit canned.
If the Bears are ever going to fix their offense, they need to find an OC that isn't a moron. Then fix the oline. Then draft a QB and develop him.