Softer than crib mattress for sure. I've been laying on my kid's crib mattress now that it's in the toddler bed and it's rock hard! I feel badly for him that he's stick with it until we get his trundle bed ordered! My older son has the best mattress on his full bed. I love it.
Re: Does it matter what kind of full mattress we buy?
Pick what you would want to sleep on.