I think both are worth it.
I'm actually going to Kauai tomorrow and for this trip I've booked a Na Pali coast cruise tour with snorkeling.
I will point you to THE very best series of guide books to all of the major hawaiian islands: The Hawaii Revealed Series.
https://www.hawaiirevealed.com/kauai-revealed/
Get it from amazon or get it free from local library. The author actually lives on Kauai and has EXTENSIVE knowledge and in this book there's stuff that even locals get surprised by.
He has a GREAT section reviewing boat tour companies and helicopter companies.
With that said I'm booking with Holo Holo for the Kauai boat tour, since they go all the way fairly north up the na pali coast then they go to Niihau (forbidden island) as well and come back for a great 7 hour trip.
Blue Hawaiian is recommended for helicopter as is Jack Harter helicopters (these guys let you take the doors off for an additional fee) But realize in general helicopter tours are about $300 or more per person and will last about 1hr. Boats are less than $200 and can be 4-7 hours long with food and snorkel equipment provided as well