Would Typhoon Lagoon or Blizzard Beach be better for a 5 yo? It's been several years since I last went to either water park--so I don't really remember the differences between the two.
My daughter was 8 when we last went to WDW and we went to Blizzard Beach. A couple of years younger before that, we took her to Typhoon Lagoon. By far she enjoyed Blizzard Beach more. We did too.
For a 5 year old, I would definitely say BB. The wave pool at TL is awesome, but intimidating and powerful with the huge waves. The slides and other things are comparable and the theming of BB is much different. TL is tropical, not a lot different than the standard FL stuff. Where else can you swim in the snow?
I'd tend to agree on BB. My girls loved it when they were small and clearly favored it over TL. Now, they are 11 and 14 and want to do shark reef and Humunga . BB is just more little kid friendly. Either way, it's still a Disney park and there is plenty of fun to be had at both!