Hi,
I've been to the Merengue twice and have only come back from the Victoria a couple of weeks ago. I enjoyed them both but I would say the Merengue definitely has the edge depending of course in what you are looking for in a hotel.
The Victoria is much smaller and much quieter - geared mostly towards adults I think kids might be bored here. It's set on the golf course (not on the beach) but it's only a 5 minute walk away and there is a bar and restaurant ther for guests during the day. I didn't think much of the buffet food at the Victoria - in fact we only ate dinner in it once but the al a carte restaurante and especially the pizzeria were very good.
THe Merengue's food was better and in general there is more to do. It does have the advantage of being part of a larger resort so you can also use the bars and restaurants of the Riu mambo and the Riu Batchata if you fancied a bit of a bar crawl one night. At the Victoria there are only 2 bars open in the evening which both close at midnight so if you want a late drink you're out of luck. At the Riu there are disco is open to 2am and I beleive there is a bar open at the Batchata which closes when the last guest leaves.
The rooms were larger and nicer at the Merengue as well - the Victoria was OK too there is just no storage space for clothes whatsoever - luckily we were only staying for a week so didn't have that much stuff - it would have been a real problem for 2 weeks. The Merengue also has a great included room mini bar with optics of Rum, Vodka, brandy etc and soft drinks in a fridge if you fancy a drink in your room - the Victoria only has a fridge with 1 bear, 1 7up and 1 coke in it.
The Victoria did have the advantage of it being very quiet but given the choice I would vote to go back to the Merengue next time.
Hope this helps
Tracy