"Better" is the Boolean
operator you still have to define on the set of techniques, but I doubt you can do it. Better for what? It makes your question invalid.
All types of validation have its importance. In every specific case, certain subset of them should be used, ranging from "none of them" to "all of them". But you've built the set of techniques not quite correctly. The mistaken one is about the server-side validation. You should have written just "server-side validation". Depending on the
validation criteria you may or may not use Regular Expression or something else. By the way, asking questions on how to use Regular Expression for some criteria where this technique it totally unsuitable is one of the typical mistakes we often see on this forum.
—SA