The best soleplate will depend on your needs. For instance, if you iron once a week or less frequently, and the garments are usually cotton shirts, denim, etc., a stainless steel soleplate will work best for you.
On the other hand, if you iron more than once in a week and mostly synthetic fiber clothes like polyester, go for ceramic soleplates. If looking for a lightweight and rugged iron that will suit all fabrics and also last long, go for irons with titanium sole plates.