I prefer CSR to AKL. Last time we stayed at AKL housekeeping seemed to have really slipped, and that was a big issue for us.
Since staying at CSR we've found it hard to justify the price difference of the two hotels.
Restaurants: I do prefer the Mara, but the CS at Rix's has met our needs while staying at CSR. I haven't eaten at the Pepper Market in a long time. It was fine, but we don't like the setup, so we go to Rix's instead. We've never eaten at the TS at CSR. At AKL, Boma was a little disappointing to us, but Jiko is great. I've never eaten at Sanaa, but I've heard great things.
Pools: The pools are pretty similar. You have zero entry at AKL, but a better slide at CSR. The pool at Kidani is more impressive with its water play area, but I think that's only for the smaller kids.
The Room: AKL does have a balcony which is nice for the extra space, but otherwise the rooms are about the same size. You have interior hallways at AKL and exterior at CSR. The hallways at AKL are LONG. You do get to see viewing areas as you walk though.
Resort Size: CSR is a big resort. We've stayed in all three sections. We like the Cabanas the best being between the main pool and El Centro. AKL is more compact, but again, you still have a hike to some rooms.
Transportation: CSR is a lot more centrally located, so shorter trips to the parks and better bus transportation.The bus trips from AKL feel long, I don't recall ever having that issue from CSR.
The lobby: AKL wins hands down, the lobby is gorgeous, and there's a lot of seating to lounge in. There's also the outdoor viewing area right off of it. CSR doesn't have the type of lobby you would hang out in. It's pretty enough, but nothing to write home about.
If you decide to go with the split stay, I would book pool view instead of standard at AKL. Normally, the price difference is pretty negligible, and the pool views in general are very nice. The only downside is that you give up the possibility of being placed in a room that's on the Savannah, but wasn't deemed worthy of the Savannah designation, so instead it's in the standard category. Of course you would be guaranteeing that you won't be looking at a parking lot. The pool views are also pretty close to the lobby, so no hiking necessary.
I also would highly recommend ASmu over Pop. We really enjoyed our stay there. It's a pretty compact resort. It's not on the same level as the Mods and Deluxes, but we thought the pools were cute, we had good experiences at the food court, and the bus transportation met our needs. The rooms were also fine, well kept, and clean. We were going to stay at Pop. We got to our room and it had an incredibly fowl odor. I have no idea what that smell was, but it was horrible. I did not trust the housekeeping staff at that resort knowing that they deemed that room ready to be inhabited by guests. We asked to be switched to another value. Thankfully, they found us another hotel to stay at. From our brief stint there, I also can note that I prefer the theme of ASMu, it's much more Disney. Pop was more sterile to me with the decades theme.