We've been to Lac d'Ailette.
The setting is lovely, with wooded lots and a sandy beach. The dome area has lovely decking onto the lake.
We didn't have babies or toddlers, but it looked really well equipped for them, with plenty of safe areas to park them in the pool, and their own indoor play area. The Wannabee/quand je serais grand activities went up to about age 12, which was good for us.
We had pretty rubbish weather, so spent a fair bit of time in the bowling alley/sports bar, where there was free wifi.
The accomodation was in pretty two storey cottages, but the one we had was not nearly as spacious as the same occupancy/standard as the one we stayed in at Kempervennen in the Netherlands. Kempervennen was also better for sports facilities.
The one thing going for Lac d'Ailette is that it is in France and I speak French. Other than that Kempervennen wins hands down. The language thing is really minor as everyone speaks English in both places.
When we went to Lac d'Ailette we spent a couple of days in Paris (prior to arrival), which was good, and similarly went to Amsterdam when we were in the NL.