save your money, The Apple Milanese Loops are way over priced. My wife likes them so we bought one through Amazon for $18 in rose gold to match her watch.
If I didn't already have the AW4, I would try to get that as opposed to the AW5. The AW3 42mm gets about 70 hours on battery. The AW4 about 40 hours due to the heart monitor and other stuff always on. (Both are Cellular) The 5 may be even less battery due to the always on screen and additional health constant monitoring. The longest lasting battery was my original AW 42mm stainless which was non cellular which would often get 80 hours.
Also, if battery life is important, go for the larger size as it has the bigger battery. My wife was concerned about the 42mm AW3 but I talked her into it and now she is used to it, never complains. She recharges every 3rd night. Her AW3 is also a cellular model.