Runescape membership?

I play runescape my account name is Spierbal 30 and i dont know if i should become a member ? my stats include wc = 70 mining 61 str 63 att 61 and def 51 and fletching 45 and crafting 40. will someone tell me if i should become a member or not and what would be the advantages if i did?? :) thanks :)