After "wasting" one summer shooting 270 WSM, I can assure you that 300 WSM is way superior to 308 Win but you should never get one as your first rifle!
Simply get a 308 Win or, even better, a 1-7" barrel twist 223 Rem and master the basic. Once you've covered the basics, you can then decide if you really need something "better".
Most big boomers are simply not fun to shoot because of high recoil and higher costs.
Alex