Welcome to the site!

Judging from your screen name it looks like you're leaning in the direction of the 7mm

There are lots of cartridges from which to choose - are you just talking about bullet diameter or are you specific to the .308Win and the 7mmRemMag..?

Where are your hunts?
Is this close wooded stalking or tree stands or wide open ranges ..?
Have you been out scouting?
Is there additional budget for binoculars and a pack frame and other field gear?

It's great you've chosen to pursue hunting.
Don't beat yourself up on caliber choice, soon that step will be behind you and you'll be in the field!

Cheers
Tinker