The Maruzen L96. It's very expensive and discontinued, but you can find it at a couple places for $350-400. Your other option is to get a clone L96 (all other brands are clones, and have similar shitty quality) and replace everything except the externals: this would include: inner barrel, hop up, trigger mech, and cylinder set. This could run you as little as $350-400 + the $150 for the gun/scope. That would give you a decent setup, although the externals would not be as high quality, and you can easily go higher on better internal parts.
Keep in mind for a clone to be any good all the internals have to be replaced and for it to feel good all the externals need to be replaced and the stock needs to be worked on ($450 for barrel/receiver/endcap+elbow grease). Whereas the Maruzen shoots accurately out of the box
The VSR but you will still need to upgrade it with Sears, spring and hop rubber to get anything over 350 fps out the box. If you want power with comparable accuracy a BAR 10, basically a direct VSR clone, but this again will still need to be upgraded in the hop and Sear department for good accuracy and longevity.