If you know you will always have time for that perfect shot placement 243. However if your style of hunting doesn't always allow for perfect form or there are hounds pushing him I prefer 06. The 06 will provide the Down range KE the 30-30 just doesn't have. If you are only taking still hunting type shots and don,t want to wipe out whatever quarter you hit 243. If you want to kill regardless what it look likes when it comes time to process 30-06.
Just my 2 cents after 40 yrs unknown first hand accounts and well into the 1000s of tracks, skinning, and processing.