I'm a hard no on recommending the Alphafly. They have a Zoom Air pod on the bottom of the shoe, and mine popped after 100-150 miles (maybe?) which rendered the shoe pretty much useless. Maybe I got a bad design, or maybe I was too tough on them, but I'm not willing to shell out the money to give them another chance.
With that being said, I'm a big fan of the Vaporfly Next%. I've run thousands of miles in Next% 1 and 2, and have a pair of 3 with not a ton of use yet. So I can't give you a fair assessment of the 3s yet, but they didn't wow me out the box. I prefer the 2 over the 1. But in both cases, I was able to get 100 solid racing miles, 400 additional solid hard training run miles, and 500 additional moderate/long training run miles (total of 1000 miles per shoe) out of them. This is far and away more miles then I normally get from my Saucony Ride (350 miles) and Kinvara (150 miles) just for comparison. My data is debatable as to whether the shoes have made a measurable difference in performance, but it definitely feels like a fun shoe to race in. It feels like it's helping you/encouraging you down the road.