I'm a big fan of the 30/06 , I've either owned or shot most of the calibres available except for a few of the new short magnums and I keep going back to the 30/06 , bullets are available for it from 100 gn up to 225 gn , cases are always available and so are projectiles , I use it on every thing from dingoes to scrub bulls , it does the job with out any fuss or bother ,
Before I cleaned out the safe I had 4 rifles in 30/06 , and I think from memory I've owned some thing like 8 or 9 rifles in 308 and have loaded pretty much bullet weight for it but still prefer the 30/06
That is not to say there is any thing at all wrong with the 308 , I just prefer the 30/06 , as a reloader I think I get more loads from a 30/06 case than I do the 308 ,
For various reasons I don't much like the 22/250 , 220 swift , 243 , 270 and 7mm rem mag but much of that is personal preference
I do really like the 223R , 257 Roberts , 6.5 x55 . 7x57 , 308 , 303 and 30/06 but the last three are the only ones that can be counted on to preform on big and small beasties at all times in all conditions
There is nothing wrong at all with the Ruger , fine gun , my 30/06 is a Marlin XL7 and it's possibly one of the cheapest rifles I've owned but it shoots as well or better as the more expensive guns I've owned and the trigger is great out of the box
I've sold off a lot of the rifles I had over the last few years as I just couldn't be bothered loading for them any more and I found that I just wasn't using them , I find that for all my shooting I either reach for a 22 rimfire or the 30/06 , still got a 35/303 and a 303 and a 45 lever gun but I don't use them except on the range and the 45 is the gun when I want a gun for travelling when I think I won't need a gun ,
You won't go wrong with a 308 but if you can get one in 30/06 for the same money even better
David