Best park in my opinion.
Why you ask?
Well they have pretty standard features in terms of rails in addition to jumps ranging from 5 ft to 70-80ish ft. They definitely cater to every ability level. Its not the best park in the world or anything.
However, Vail beats Breck and Key in terms of crowds, lift time, and general vibe. You will see a maximum of 10 other skiers in the park so you pretty much have it all to yourself, which is great if your self conscious about people judging your ability level. Additionally, I have met a lot of great people in Vail's park and usually end up riding with a stranger for a run or two. The lift ride itself takes about 4 minutes and there is never anyone in line considering that there really isn't any good skiing for people just looking to rip.
Sparknotes: Average park (still a lot of fun), no liftlines for park lift, lift ride is 4 minutes, no judgemental, hate filled goons in the park, no one in the park in general, great overall vibe, and those who are in the park are usually pretty friendly.
I will be up there every chance I get for the rest of the season. I'll be wearing a tie dye helmet. If you see me, give me a shot, we will take some runs, and enjoy spring skiing.