My son loved Legoland but he loved Legos. Do your kiddos love the toys? They are a good age for it. We’ve only been twice though and we do Disney a lot but that’s because of me. It was a nice change up.
Edit both my daughter and I loved the Oogie boogie Halloween party when she was 12. If it were me I’d choose that
My kids aged 6 and 8 still think Legoland (California) is the greatest place they’ve ever been, and they have been to both WDW and Disneyland and several amazing beaches, resorts, destinations, etc. They are somewhat wimps when it comes to big rides though. If your kids like thrills, they will be bored at Legoland. If they like legos and tame rides, they will be in heaven.
The water park in California was also great. I can’t speak for Florida, but I’m sure it is similar. They were afraid to go on most of the slides, but there was plenty of other fun stuff.
We managed to see most of the regular park and the water park in one day, though I was glad we had a second day to catch what we missed.
Disney’s water parks are better than Legoland’s but comparable for kids, unless they like the big slides - if so, Disney would be more fun.
I wouldn’t count on a Halloween party this year, but it’s possible.
I have been to Legoland and Blizzard Beach. Legoland was . . . fine. It’s honestly difficult to go to any park that isn’t Universal or Disney as none of them have quite as good customer experience. They have a for-fee fast pass type service, which I strongly recommend.
The Disney water park is the most amazing water park I have ever been to. I was honestly meh about going, but my family wanted to go, and I had an absolute blast. I would go to Blizzard Beach over Legoland any day of the week.
A few other notes - LegoLand is largely outside, so if it rains, there’s not a ton to do. I would definitely try to adjust your schedule around weather if you can.
Also - Lego usually has a special that is “buy a Lego set now, get BOGO Legoland pass” in the spring / summer. Keep an eye out for those as it will save you a ton. And if you are a Lego VIP and have points, you can cash them in for Legoland passes!