I've stayed in both and there is literally no comparison. AKL is magical with so much to see. Try to get a savannah view room so you can wake up and watch the animals off your porch. Participating in drum lessons is also fun and watching the man carve the walking sticks is amazing. There is just so much to see and do there. The food is great at Sanaa and Boma (I prefer breakfast) and the pools are great.
Bay Lake, to me, felt like a regular hotel. Sure, it's close to MK, but to be honest, I'm so exhausted after walking the park the last thing I want to do is walk...anywhere. Give me a taxi, minnie van, or bus. AKL is really big so you can ask for a room close to the lobby or buses to cut down. If you do stay there, keep in mind there is Jambo house and Kidani. Two separate areas though side by side. Their lobbies are vastly different and for a first time, I would suggest the main lodge (Jambo house).