Both have kiddie areas and both are a lot of fun.
However having down both with preschoolers, I (everyone else in my party and family, inculding the kids) think BB is better for the 5 and under crowd.
Pikes peak is more protected, one way out, one way in. It has less "spash water in your face play" Many young kids, mine especailly don't like water right in their face. It has more slides that adults can accompany children on, the wave pool is milder (TL wave will knock over a tolder or even 5 year old, mine was pretty scared of it, but loved being held in the rolling waves of BB wave pool.)
TL has a few different kidie areas spread out, so you might have to slpit up, one go with the 5 year old, one with the younger child. It was harder to see from one end to the other at TL. BB was easier.
My kids also got a big kick out of the BB theme. They liked the mealting snow many and crazy alliagtor. Didn't get the whole "storm" them of TL.
If you have your (or someone elses) heart set on TL, you still will have a great time. It is fun and there are things for kids all ages.
In general BB is better for the younger crowd. We enjoy it more. A CM mentioned that before we went, and after going with kids we understood what they were talking about.