You cannot know until you have tried both! That's the truth of it. None of us get to try these things out, it's only a guess. Stop feeling so guilty. You're doing your best.
FWIW the RC one sounds better in that his friends are there, (big deal to a little one) and also it's smaller. Probably there are more staff to children.
The one ds1 started at was also very very good, great results etc and very competitive to get in but in fact, it was HUGE, much too big, chaotic, he was often totally lost among the hundreds of reception children, he got beaten up, never ate any lunch, no one was available to talk to EVER.
I took him out. He got offered a place at our first choice, in yr1, and went there - totally, totally different setting, the infants are very well cared for, no one gets beaten up, or lost. everyone eats their lunch because someone is helping them and checking they are all Ok.
I'm so glad we moved as ds2 has gone there as well now and was fine in reception. It's great.
But if we hadn't tried the other one we'd never have known how chaotic it was. I know it's still great for older kids and so on but imo the smaller your reception numbers, the better.