Rider,
Nothing wrong with the 270. Little better bullet selection with 7mm over 277 but there are plenty good bullets for game in the .277 bore.
270 will push a little more a little further a little faster-that's it.
Depends on what you want to hunt with it and at what distances. Bullet selection and shot placement are even greater issues.
If you are considering elk class, hten I would encourage you to consider the 270. If you really like the 7mm bore go with the 280 or 284 Win.