The only other field I have played at regularly is The Badlandz in Crete, IL. To compare however, I need to break down some differences.
As far as prices go, both of the fields are great. Low access prices and BYOP is excellent.
In field quality, Fort Knox is far superior. The buildings and bunkers are incredible. You can really tell that the owner of Fort Knox has put a considerable amount of time in designing and building his field to maximize the enjoyment factor for the players compared to The Badlandz where most of the field is disintegrating.
Field Facilities are also far superior and more taken care of at Fort Knox. Everything is clean and well kept and nothing seems to be falling apart.
That is all I'll say here.
I've played at Fort Knox three times over the past 4 years. The first two times were with my church on a men's retreat and the third was for the April, 2010 "Chronostorm" Big Game.
The field is flat out fantastic. You can really tell that the owner wants the player to have as much fun as possible. The design and execution of the structures all over the field assure the walk-on player a variety of playing options and excitement.
It's like being a kid again looking at the pictures before you even arrive at the field. I got excited to play this field from just seeing it online. From the Castle to the Pirate Ship to the Wild West Town, this field is full of well maintained and super fun fields and buildings to play in, on and around.
The field is clean and well maintained. The same holds true for the up front buildings as well. You walk into a professional and comfortable registration building that is comfortable to for the players as well as the workers within.
I know that both times I came to Knox with my Church group we had a blast. The ref's were very good and knowledgeable and made sure we got as much trigger time as possible. They had a wide range of games to play as well as just the general firefights.
The only bad thing I've ever experienced at Fort Knox is the Big Game. With a large pond in the middle of the field it always came down to a standoff at either the Pirate Ship on one side and the Castle or the Bone Yard on the other side. There seemed to be no way around ending up in a standstill firefight in these two areas. The other bad thing about the Big Game was the missions, or rather the lack-thereof. My team is a missions oriented team. Yet no matter how many times during the day we'd ask our General for a mission, the only thing he ever told is to do was to guard the props. This lack of missions got very old very quick, but it was all we had to do for 2 days. Now don't get me wrong, the constant firefights were great. But if you're looking for something with different challenges throughout the day, then go elsewhere for a Big Game.
Aside form that one matter, I'd wholly recommend Fort Knox to any player, either beginner or advanced.