Hi Nnyan,
Post #2 here includes links to most of the better forum topics about children and mattresses that may be helpful.
A forum title search on “year old” (you can just click this) will bring up about 5 pages of posts (20 to a page) to scan through that will include parents with children in the same age range as yours that were looking for a mattress…
Both of the options you are considering are members here (which means I think very highly of them) and they would make good quality/value choices but I would also make sure you talk with them to make sure they are firm enough for your girls (or that you choose a suitable firmness level) because children tend to need a firmer sleeping surface than most adults.
Phoenix