oh I totally feel for you! For the past few months I have been agonizing over which resort to go with.
Originally we had chosen the Melia Varadero (had a date/time booked with the resort WC) but we kept looking at the Iberostar Laguna Azul. There was nothing wrong with the Melia - it is gorgeous, has mostly amazing reviews, they really know how to do weddings and of course it's free with over 22 guests. After hours of research, going back and forth and this forum we switched and went with the IBL. We even took a vote with our guests LOL.
We started thinking how nice it would be to stay somewhere new and fancy, and thought our guests would enjoy it as well. The downside is cost, and being that it's new it may not have everything up and running smoothly, but we're just gonna go with the flow and enjoy paradise!
The best advice I can give you is to just research as much as you can - read reviews, look at pics and if you're using a TA ask her/him for advice. If you think it would help you could even ask your guests what they think. You can't go wrong with either chain, so wherever you pick will be amazing! Good luck and if you need any advice/help or just feel like you're gonna pull your hair out send me a msg.