We own and love Riviera and only do one or two-bedrooms. Our kids are now 9 and 10 (girl/boy,) and have enjoyed all the pools in different ways.
We visited friends at the Kidani pool this last trip, and while the pool itself was kind of shallow and more younger-kid aimed (perfect for you though,) we all really enjoyed the poolside activities and tie dye, etc. It seems like a really hopping pool for the kids at your age, which is nice if they don't have a sibling/friend/cousin they're traveling with. Our kids just start chatting with other kids and swim together/go down the slides with whoever is around.
Since you'll have a car, we REALLY unexpectedly LOVED OKW. Granted, we got building 12 near the Hospitality House, which was an ideal location for going back and forth for food and pools and stuff, but that sandcastle slide is a good one, and we loved the whole pool area. Good's to Go had really good poolside food, and Gurgling Suitcase great drinks. We loved taking the boat over to Disney Springs, and the kid rec center/community hall was WONDERFUL for all sorts of arts and crafts and stuff. Again, tons of kids of all ages that our kids played with, which was fun for everyone.
BLT, we haven't stayed at, but we did tour. It is 100% not our vibe at all, and the pool area looked very unappealing to us.
SS, really awkward layout with bathrooms and foyer. (I know you didn't ask, but it's a low-point option usually available.) We didn't stay long enough to try the pools, but I hear they're good.
Boulder Ridge I can't wait to try out. We love Wilderness Lodge, and I was just waiting for the refurb to be finished. The rooms look wonderful, and the pool looks peaceful -- but that may not be fun for the kiddo if there's no one to play with.
Poly pool is always hopping and is very cool.
I'm in the minority here, but we did NOT love Stormalong Bay, and our kids were older and excellent swimmers when we went. No WAY I'd be bringing a kid under 8 or 9 there. Way too stressful with all the blind spots, having to leave the actual pool area and cross the sidewalk to get to the slide, not a lot of chair space for lounging, and it's kind of a zoo when we went. Nothing relaxing over there as a parent who has to either do the "watch me!" thing all day or panic every time the kid disappears around another corner -- or having to follow them down the slide ALL FREAKING DAY because they're too little to go down alone, and I don't love the idea of the unattended child leaving the pool and crossing the sidewalk to get in line for the slide anyway. Stressful! I'm sure it's awesome once the kids are older, but for littles, no way.