In order,
-Lanai
-Hawaii
-Kauai
-Maui
-Molokai
-Oahu
Lanai has 2 spectacular resorts (with price tags to match) but the island has an authentic Hawaii vibe to it. The best of the bunch with incredible natural beauty.
Hawaii has the most to see and do, the best resorts, the best golf, the best beaches, and best restaurants. One of the few places you can play in the cold and snow and be back to 85 and sunshine at the coast in 90 minutes. But it is a Big Island that requires a car and lots of driving to see the diversity it offers. When there's active lava flows, this island moves into first place.
Kauai is small and approachable with lots to see and do...and amazing scenery and beaches. But in the chain, the weather is more wet and unpredictable than other islands.
-Maui is an extension of southern California. Excluding the high country up to Haleakala or the road to Hana, Kihei, Kahului, and Kaanapali could easily be an extension of Orange or even San Diego counties. Place feels more like California than Hawaii, although the ocean and mountains are more pretty. Lots of traffic and in non-pandemic times, too many tourists.
-Molokai is rustic and senic...and super authentic. But not really made for traditional tourism. And no upscale resorts. A tiny island, this may make for a nice add-on to a longer stay to one of the other islands.
-Oahu has must-see Pearl Harbor and stunning coastline along its north shore. But it also has Honolulu's traffic, noise, and sky high prices and fees. Doesn't necessarily feel Hawaiian here, although if you like urban jungles in warm climates like Miami, etc, this could be up your alley. Of the bunch to visit, I'd put this last.