Crazy mofo here, thinking of buying another airsoft gun so quickly, I am debating over

M4A1 (a one with rails for red dots .etc)
M16 (can be a vietnam era or a modern one)
STG44
Thompson 1928
MP5 (extra rails or a silencer)
G36 (I went to take my learners permit for driving and my number on my ticket was that )
MK16-L (H if they have one)

Just my budget is gonna be tight again to around $170 to $270. Oh if its close to $300 then it's all good depending on how pissed my parents get.

So pointers, links, and help would be nice.