In your case then don't get an M14.
If you want Accuracy and durability and don't care about any other aspect then I would highly suggest a more common platform. The AK or M16 will do you fine in those regards.
Get a decent base to start with (ie. a "name brand" such as TM, G&P, VFC, CA, etc.). After that, toss in a TBB (6.03mm is what is recommended instead of a 6.01mm IIRC) and a quality hop up unit and rubber (ie. Prometheus Neo Hop Up unit, and a Prometheus soft rubber) and you'll be laughing all the way.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE