Should I play Oboe, Violin or Piano as second Intsrument?

Hi , I was thinking of doing another instrument because I really like music and think it will help my learning of music for my GCSE. The first instrument I play is an alto saxophone and so far for 1 1/2 years. I am thinking of piano because i can play all the scales and octaves and many pieces but I can't really play using both hands really well. Violin because I can play many classical pieces and I like doing solo. Or maybe oboe because yesterday I heard my friend play who is grade 8 in oboe and she played concerto Mozart and I thought it was beautiful plus I could learn during summer holiday and practise loads and I think I could do good because I might think of having my friends tutor also :) so which one. I don't really care about difficulty because I swear I will practise so much.