G&G Combat Machine M4 if you're looking for an M4 style weapon.
CYMA AK (model numbers CM.048 and above) or G&G RK-47 if you're looking for something a little more Eastern.
G&G/Classic Army MP5 if you want an SMG
SRC Gen 3 G36/Classic Army G36 if you're interested in that sort of thing.
If you're looking to start airsofting properly, I'd recommend you buy yourself a decent pair of ankle supporting boots, some cheap combat clothing, a fairly good lower face mesh guard and ESS ICE or similar high end goggles/mesh goggles.
You may also find a battery and charger useful when you buy your 1st AEG, and extra magazines/batteries would come in handy as well so you don't have to wait for flat batteries to charge at a skirmish.
Use the links Mack's provided, he replied just after I'd finished typing this massive paragraph