hardrockr1010
Maruzen is a great brand. Many aftermarket parts are available for their l96 variant. Another good brand is Tokyo Marui and their VSR rifles. They also have a lot of aftermarket parts available for those rifles. But beware...if you want the best rifle you are going to be putting in at least $1000 to the sport of airsoft. Though, it will most likely exceed this amount if you truly want a good sniper rifle.

JV-
Easy one, WELL. WELL makes the best snipers and they all around $100 bucks if not cheaper. They have an L96 for around $85 on Airsoftmegastore.com