score:12
I just went through and looked up all the ratings. Below is the list of National Parks, sorted by rating and then by number of reviews as of September 1, 2016.
National Park Rating Reviews
-------------------------------------
Badlands 4.9 549
Virgin Islands 4.9 94
Arches 4.8 851
Sequoia 4.8 805
Acadia 4.8 729
Carlsbad Caverns 4.8 466
Rocky Mountain 4.8 463
Grand Teton 4.8 263
Olympic 4.8 246
Dry Tortugas 4.8 177
Black Canyon of 4.8 133
the Gunnison
Grand Canyon 4.7 2129
Yosemite 4.7 2041
Zion 4.7 1591
Bryce Canyon 4.7 994
Mount Rainier 4.7 743
Crater Lake 4.7 707
Redwood 4.7 515
Cuyahoga Valley 4.7 407
Big Bend 4.7 232
Lassen Volcanic 4.7 223
Canyonlands 4.7 197
Theodore Roosevelt 4.7 180
Kings Canyon 4.7 128
Great Basin 4.7 86
Katmai 4.7 24
Yellowstone 4.6 1880
Shenandoah 4.6 643
Great Smoky 4.6 581
Mountains
Joshua Tree 4.6 417
Haleakala 4.6 404
Great Sand Dunes 4.6 306
Pinnacles 4.6 219
Saguaro 4.6 200
Guadalupe Mountains 4.6 84
Congaree 4.6 74
Death Valley 4.5 637
Hawaii Volcanoes 4.5 528
Mammoth Cave 4.5 526
Capitol Reef 4.5 209
Wind Cave 4.5 112
Isle Royale 4.5 70
North Cascades 4.5 53
Kenai Fjords 4.5 38
Lake Clark 4.5 13
Channel Islands 4.5 9
Everglades 4.4 339
Hot Springs 4.4 232
Biscayne 4.4 124
Glacier Bay 4.4 54
Gates of the Arctic 4.4 35
American Samoa 4.4 13
Petrified Forest 4.3 302
Voyageurs 4.3 24
Kobuk Valley 4.1 14
Wrangell - St. Elias 4 18
Mesa Verde 4 unknown
Glacier 3.7* 383
Denali 3.7* 175
* Glacier and Denali National Parks both stated 3.8 with no review count on the Google homepage, but 3.7 and review count when looking on Google Maps. I do not know why there is a discrepancy, but all other ratings are from the Google homepage.