I've been a 7mm guy for a lot of years, several 7mags, a 7prc, 280ai, and 7-08. I think the 7-08 with light loads would be great for a starter and then moving up as they get older...
That being said, the last few years I've started carrying my .223 for everything. I live in ND and don't have to worry about a blood trail. I'm starting a 6arc build just for fun that would be a good one too. If I needed a blood trail I'd consider the 6.8 SPC, I used it a lot in TN taking youths out hunting and was never disappointed.
It's really up to you. Any of the CM or traditional short action cartridges will work. If you don't reload, I see what is most available locally and at price you wanna pay for practicing... The 6.5 cm in my area is the easiest and cheapest to find ammo for other than the .223 and 22lr. I've killed deer with the 6.5 cm and .223, they didn't know the difference or even if they were shot with a 7mag.