This is a reoccurring question. as to the sps, many people like them as to say you should get one only you can answer that.
As far a .308 vs 30-06 been drilled many of times, with modern ammo the .308 will kill just about anything you need, the 06 will defiantly kill anything in the conus. I have a 30-06 just for hunting (heavier bullets) and I am working on a .308 for paper and fun.
Not too mention target/tactical rifles are a bit heavy and can take a toll on the hunter.
There is no one-size-fits-all solution to this question.
For target/long range shooting you want to start with a heavy barreled 308.
For a hunting gun that you carry all day and maybe fire 2 shots, a light barreled 30-06 or 270 will fit the bill best.
You have to decide what are you going to do MORE, target shoot or hunt, before you can determine what to buy first.
The proper solution is to buy one gun for each purpose.
The hunting rifle will end up with a lower profile and lower magnification scope.
The target rifle will end up with a bulkier scope with more magnification.
Setup properly for their tasks, neither gun does a really good job at what the other gun is set to do.
I like the '06 because you can launch 208gr AMAX pills at about 2700fps or move to light bullets for varmint. Its incredibly versatile and brass is fairly cheap as are quality factory loadings.
However, if you plan on shooting a whole lot the .308 will be cheaper to feed and is still a capable round.
Stick to the 20" .308 until the barrel is shot out. By then you will have figured out your needs.
If you really like longer range shooting, rebarrel to 6.5 Creedmoor or .260. That lets you keep the same bolt face and everything, but gives you much better ballistic advantage.
Well to be fair he could run a brake. Added expense but its a soft round with a proper brake. But I have more years shooting '06 than .308 so I may be biased.
Get the 20 inch, 5R 308 threaded, put an AAC adapter / brake on it. It will shoot like a cream puff and you can shoot and learn and shoot and learn and shoot and learn…