.30-30 is a blunt-nosed round designed for lever action rifles. .30-06 is a pointy-nosed round designed for bolt-actions with stacked magazines.
So, if you have a preference in rifle type, that may make your decision for you.
The aerodymanics of the .30-06 are better and more stable at long ranges.
the 30-30 is a carbine that shoots essentially pistol ammo. I had one once and loved it. I needed some arm rehab, though, and traded it for a compound bow and a pile of arrows and other bow stuff. That was great, too.
The .30-30 has ballistics similar to the M43 round used in the AK-47, but normally uses heavier bullets. The .30-40 round was developed about the same time, for the Krag, and has similar ballistics (but uses a really slick bolt action and a 5 round ‘drop in’ magazine, permitting pointed bullets.
The .30/06 has factory rounds from 110 grain to 220 grain, and has been used on everything from prairie dogs to Cape Buffalo. It can be ld oaded from gentle to near magnum. You can even get tracer and armor piercing rounds, depending on our local laws.
The thick rim on the .30-30 makes it easier to accurately head space the round in the chamber, giving you a cheaper route to high accuracy. Reliable feed can be a problem if your magazines let the rims overlap.
Then take the 7.62X54R Russian. Velocity of the .30/06, and cheap head space of a Rimmed round. Alas, tracer and armor piercing rounds are usually illegal. You may have to extend your cheap Mosin-Nagant bayonet to get best accuracy.
For tubular magazine lever action rifles. For example, I have a BLR w/detachable mags.