Having used other bus tour companies in other cities around the world, it's safe to say the Big Bus live guide is the best one out there. Not only do you get the usual commentary on points of interest around the routes, but being a live guide tour you also get additional commentary (and jokes!) based on what's happening right there and then. When the bus has to detour due to road closures for events (thanks Joe Biden), the guides can adapt to the alternate route with ease, so it never feels like a detour.
Special mentions to Lionel and the ginger lady* for excellent and funny guides.
* I forgot your name, sorry! And I won't call you "Melissa" because it was a great guided tour!