We have stayed at both Pop (right next to AoA) and the Contemporary (both garden and tower rooms). Here's how I see it:
Contemporary - hands down, the MOST convenient resort to MK. The walk is about 10 minutes. Yes, you can take the monorail to Epcot (with a monorail change at TTC) but really it still took us about 40 minutes door to turnstile which is a long time. The bus transportation to DHS and AK is very poor in my opinion. Each time we have gone, it shared with the Poly and GF and sometimes WL. The buses pick up at Contemporary first (which is great for getting a seat as opposed to standing) but then stops at the other resorts which makes for a LONG transit time to DHS and AK. Usually took us about 45 min each.
As for dining with the Contemporary, we have done Chef Mickey's several times and it is fun. It is also nice to have all of the other dining options of the other monorail resorts and WL. Also, you are just a quick boat ride to Hoop Dee Do if you are interested in that. The counter service restaurant is very good at the CR in my opinion. Very rarely crowded and above average food.
As for the garden vs tower rooms. Each has their pros and cons. They are all the same size, shape and decor. Garden rooms are very close to the pool, beach, laundry. The farthest rooms are a bit of a walk for sure. But the close ones are very close to the main building and probably a 1 minute walk from the main building. The tower rooms are obviously closer to the monorail and restaurants but are far from the pool and laundry. I personally would not pay for a tower room (we were given a complimentary upgrade from a garden room). The one difference is that the 2nd and 3rd floor garden rooms do not have a balcony. The 1st floor rooms have a very nice patio. So if you MUST have a balcony, book a tower room.
Now for Pop (or AoA). I was surprised at how much we liked our stay there. We found the location to be perfect. It was so close to DHS and the bus rides to the other parks were very reasonable. No one park was a long ways away (like AK is for the Contemporary). And, they have specific lines for the buses which I like because I hate waiting and then have a ton of last minute people show up and take all the seats. But the best part of the transportation was that it had dedicated bus service, meaning it didn't share with any other resorts. Once you got on the bus you headed to the park. The theming was very Disney and my kids did indeed love it. We had a preferred room and it was so convenient to the pool and restaurant.
We are in the middle of making a similar decision. I'm not sure how we'll swing yet. Love the room sizes of the CR and the location but the price, not so much.