Last year I drove to Gateway Arch, Indiana Dunes, Voyagers, Isle Royale (took the boat) and Conagree, thus completing my visits to 54 separate parks. (By the way, the 3 newest parks are Indiana Dunes, Gateway Arch and Pinnacles, in that order.) I still plan to visit the 8 parks in Alaska and the Somoa NP.
Having a favorite park is like having a favorite child. Each is different. Yosemite is spectaular but overcrowded. If you like solitude, there are plenty of National Parks that have low visitation number.
This summer I am headed to Olymipic National Park where I can experience rain forest, tidal pools and glaciers. Later I will watch a sun rise and sun set over Crater Lake.