If this is your first real Airsoft sniper rifle, id recomend a TM VSR. Ive never owned one myself, but i have used them in the past and have heard good things about them. Their a good gun for a beginner as they have a nice ease of use. They have a good potential for upgrades (search the forums).
For your first sniper rifle, forget the term "Go big or go home". Start with something simple.