The best G36 is a pre-Ares Star G36. If Ares Is well known for it's externals, but the internals are where to be concerned.
The King Arms M4 is a great place to start. $300-$500 for your first Airsoft gun is normal, that doesn't include the cost of maintenance, upgrades, accessories (like magazines, sights, etc). Spending less is asking for trouble. For the most part, avoid Umarex, Well, UTG, Mauser, Jing Gong, Echo 1, KJW, Cyma, A&K, D-Boys, Cybergun, Etc. Not all guns made by these companies are poorly designed, but they are best avoided.
If you have specific guns in mind, do thorough research. Even well thought of companies don't make the same gun equally well. Start yourself out on the right foot, and avoid the nightmares. Remember, Even the best guns will need some work to shoot true, and last. Start off with a good platform. A company that tries to make a solid product. Not a cheap piece of crap, or a clone. With the prices that are available today, there is no excuse to buy garbage.
If you want really detailed help, have access to better and interesting parts and guns, or just want to save some money and be economical; get yourself age verified.
ďREALITY IS LIKE A STONE. TO MANY ITíS HARD AND COLD, THEY CANíT HUG IT OR EAT IT, IT ONLY FRUSTERATES THEM AND DOESNíT DO THEM MUCH GOOD. TO OTHERS ITíS STRONG AND DEPENDABLE, YOU CAN BUILD WITH IT, BUILD UPON IT, OR WORK WITH IT, ALSO USE IT TO SMASH PEOPLE IN THE FACE.Ē