Arches National Park, Utah is properly the most popular in this area out of Moab. It is closest to the town, easiest access plus the least walking involved.
When we went we were advised to get there before 8am as it was a busy weekend but I think even on weekdays it would be best to visit at this time. The people were queuing outside the park to get in within the hour of us being within. We were ahead of the crowds so all of our shots are clear of people, granted they started to catch up at the end. That is inevitable. We had a good few hours of exploring from within the comfort of our rental for the first half at least while we saw a range of rock formations.
I like Arches because you can see the full progression of how these arches are formed to what they end up looking like. The full life cycle of these rocks over centuries. No mater what stage they are at they are always beautiful and astonishing. You are never too far away from something breathtaking. The red rock is an alien landscape that is ever changing at the slowest rate that you can imagine. Something that you cannot comprehend but cannot take your eyes off.
A place that you have to see for yourself. Truly.