What's "best" will also hinge on the group you play with. Lots of people will say new players should shy away from gas because of the higher price and different style of play.
If the group is all running gas rifles and you are a seasoned player you'll find yourself pretty happy. We see new guys turn up where we are running the KJW gas rifles and they do well also so it is not impossible to start with one.
A lot of people laid the groundwork on gas rifles so the how too's on here are as good as any mechbox fixing thread. Plus prices are downright affordable for what you get.
The catch is the group you play with though. If its' all AEGs and a lot of suppressing fire and high cap mag dumps you will find it's tough to stand your ground. You will have to adapt your style of play.
If you're new then developing your skills to counter the AEGs will be tougher. Not impossible but for some people the curve is so steep this stops being fun.
Airsoft, where nothing is hurt but feelings.