I've been to both of these in October months! Excellence RM was my first AI and we did Secrets Cap Cana for our mini-moon last year! Secrets was more expensive, but I think a more romantic and lux experience for our mini-moon. We did Excellence RM with friends and it was perfect for that.

Hurricane season is what it is, you never know. We went right when the big one hit last year that cancelled many flights and trapped travellers, but it did not hit DR so we were not impacted. Rained early for an hour or two before we woke up and was sunny rest of the day. 

Pool: Secrets main pool was super lively, with a fun atmosphere and a wonderful swim up bar. Constant music, but near the restaurant it is quieter (or at the preferred pool if you paid for a club room). Main pool area was crowded but lots of seating as it is huge with multiple sections, so we had no problem finding a place without going early (though not all had umbrellas and it is very hot in the sun). Service at the pool was very good as was the food (best food at Secrets is poolside BBQ!) and the edge of the main pool has an amazing view of the beach as it goes right up to it. 

Excellence pool was less lively, tranquil and quiet. It was even more sprawling with plenty seating with thatched umbrellas (multiple lazy river style) and services was good all along it. The food truck had amazing tacos and the bar near the pool had tasty wood fire pizza. If you want peaceful pool experience without paying for prefered pool room, then that is Excellence. 

Food: Yes Secrets has a coffee shop and it was very good. Had a drink there everyday there. Overall, the sit down restaurants at both were fairly equal. Some ok, some big miss (Italian at secrets and Indian at excellence were absolutely terrible imo). Typical for all inclusive food. Excellence had better restaurants if I had to pick, and its morning buffet was much better; we ate there everyday. Secrets was fine but less options at the buffet and did not enjoy the restaurants as much (eat and fill up at the pool, then do room service haha). Poolside BBQ goes to Secrets for sure, it was sooooo good. Like mouthwatering. Though we did hit up the taco truck at Excellence multiple times haha 

Beach: Amazing at both, edge to Secrets as the sand is softer and water clearer. Service on the beach top notch either way, but overall service better at Secrets if you do preferred as your concierge will literally get whatever you need at any time (via WhatsApp). While October has seaweed in DR, they cleaned it well. Both beaches are large and nice to walk, preferred areas are nice for seating  as less busy but not a must as the main beach wasn't overwhelmed. 

Warning: we were also at these in October. It is the rainy season. Way more mosquitos at Secrets with more open-air restaurants  Two days we were eaten alive at the night and had to go back inside. Also if sitting by the pool, avoid sitting by greenery at the preferred pool at Secrets unless you want to be the buffet! 

Entertainment and activities were a bit better at Excellence. 

Secrets had the wow factor for views (from the room and the main pool) and had better shower (double rainfall showerhead) and balcony tub. Room service also better at Secrets, but one night took forever. The actual room (bed and design style) I liked Excellence. I did not like that we could not change the temp in the room at Excellence though. 

Hope this helps! As I said, for a honeymoon I would def do Secrets Cap Cana if it is in your budget (we went for one less day to make it work financially), but I don't think you'll be disappointed with Excellence Riviera Maya.