Everyone will have their own opinion on this. With both my kids they have slept wherever carseat, pram, sofa, swing and my me that works well. I won't ever use cot for nap times as they get used to it then if you go out they won't sleep get really cranky and that's no fun for anyone! My friends 2 girls do this and spend most of their visits with us crying!
My friend thinks cot for naps is best, I don't. You have to find your way hun, do what works for your family xx