Both the 7mm and 30.06 are great options. I like .308 for sport shooting (especially distance) because there is a lot of load and bullet data out there for long distance shooting. I'm training for .308 rifles though, and have equipment to reload .308, hence why I chose that particular round. There is a ton of data out there though since it is a popular military, LE, and competition round.

If you don't already have one, invest in a decent scope. Good glass makes shooting much more fun.