I was in this dilemna back when I started. I didn't know to go for guitar or bass, so I asked a friend (who happened to be a bass player), and he thought for a second about my personality, and then said guitar... so that's what I went with, and I have not regretted it once!

why don't you try describing your personality a little, then maybe we can help decide.. for example, are you energetic, or kinda laid back? do you like to be the center of attention, or are you shy? etc. etc.