Wow, good question. I love ruins and haven’t been to either of them since I was a kid. Personally if I only had time to go to one it would be Walnut Canyon.

Take care and have fun.

My suggestion is to go to Sedona or the lave tubes.
Sedona is full of hikes and things to see, like
different rock formations. They also have jeep, plane
and helicopter tours.
The lave tubes are caves formed by lava that shot out
of the bottom of the mountain the last time it
erupted. It is out towards belmont, which is 10 mile
west of Flag and requires driving on a primative road.

In regards to Walunt Creek or Wupatki. Walnut creek
has a lot of steps, I do not know how many, but a lot.
It is cool to see the old native american dwelling.
Wupatki is cool too, but it is about 30 mins outisde of
town, and the breathing hole is kind of the only cool
thing.
Any more questions please feel free to ask.

I haven’t been to either. I personally love Sedona and the Lava Tubes.