Personal taste, musical interests, then practice. If you're not feeling it, you can always try something else. The great thing about music: "when it hits you, you feel no pain.."

It's all relative to your own vibe tho. I picked up a guitar, and never put it down. But, knowing what I do now, I wish I had taken piano first, (still plan to, and drums, just wish I had sooner is all).