Buy both then.
You can buy whatever you like the most first. I'd say TM M14 is a better deal for the money.

I got an TM M4 before my M14, and now, I won't switch for any AEG. M14 rocks. Shoot to 400 fps and very very accurate. Solid stock and good range ! Only need ? Tightbore and High Scope mount to get it done ! If you are more trigger happy, don't take the M14 and go for something more little, like M4, MP5, G36c... if you are more... one shot one kill and you're sneaky to get around your targets... go for something like, the M14 ! Long AEG BTW. Very long ! But I love it !

Stock M14 shoots around 300, 310 I think, correct me If I'm wrong... Mechbox is very solid and can be upgrade to 400 fps without any mod inside it. ( Source ? Raygis and many guys who own a M14 )
Also, 8.4V only fits inside the stock. 9.6V won't get in. Good ROF with 8.4V with a lot of mah ! Hehehe...

Hope it will help.

Whats a tight bore? Sorry, I'm still kinda new to airsoft.

Normaly inner barrel come with a inner diameter of 6.08mm, tightbore are 6.04 to 6.03mm, they increase accuracy and fps (about 10-15fps).