We have the Angelcare one and I love it. We have the movement only version, as we already had a good quality BT sound monitor so we use them both together. We have a thick cotbed mattress and it works fine. With my daughter we used it in a regular cot and started to get false alarms around 8/9 months when she started to sleep hunched right up in the far corner of her cot. We turned the sensitivity up and eventually stopped using it when she was about 1, we now use a new version of the same monitor with my son as my daughter threw the old one in the bath and it stopped working! Can't recommend them enough, they are brilliant.