Whats safer to use a pack n play or portable crib?

being that pack n plays are firmer and not too soft. I dont want any issues with SIDS. and I have a bumper for a crib, its not tooo soft. and a quilt. but I am starting to think its best to use the pack n play. and If i do use it what would i want to use for a bed once my baby grows out of it? being it wont last as long as a standard size crib?