St Lucia vs Costa Rica for a June honeymoon?

I’ve been looking at Costa Rica specifically and have been trying to decide between Manuel Antonio, Papagayo Peninsula, or Nicoya Peninsula b/c I’ve heard good things about all 3.

However St Lucia has been catching my eye lately. Which of the two locations would you recommend? And what city/resort in that country?

We want:

-Romantic feel

-Amazing beach

-Activities like ATVs, waterfalls, kayaking, etc