I haven't try out most of the new guns that were released in the armory. But if you're looking for a cheap weapon that will do its job, I would definitely recommend getting either green rifle, red rifle or the poison vine gun. These guns are well priced and it's effectiveness in combat situations such as sparing and basing is absolutely outstanding. Fire rate on the gun is average, damage is also average handling is also pretty easy. There's two type of fire, auto and semi-auto, no spreads and reload well it's non-existent since it hasn't been implemented yet. Out of all the years that I have played Zone these weapons are still some of my favorite and go to weapons for spar and base. Although I vary from weapons time to time just for fun or in different combat situations.
Now if you're looking for an expensive, high-tier weapon I would recommend getting the GP Rifle. It's not the most expensive, but it is up there. GP Rifle fire rate is outstanding. Auto will have you firing at normal rate but semi-auto will have you firing one half to twice the speed of auto. Like the weapons mention above there are no real drawbacks as of right now. It is good both for basing and sparring, but i definitely recommend using it as a spar gun as it will demolish your opponents.
Hope this helps and P.S. weapon use may vary on the user and their skills.