You have to keep in mind that the caliber is NOT an indicator of accuracy. A .270 Win at full power with a 130 grain bullet will however be a flatter shooting cartridge (bullet trajectory). This is due to the lighter and faster bullet when compared to a 150 grain bullet and slightly slower velocity of a factory .30-06 spgfld cartridge. The .270 Win in 130 grain also will have a slightly better point-blank range that the 150 grain .30-06. With handloads these results may vary. With that said the .30-06 trajectory with 150 gr and 165 gr bullets is plenty flat for long distance shooting.
What you do get in the .30-06 is versitility. This cartridge is available in many more loadings/bullet weights than the just two or three of the .270 Win. I will say that the .270 Win is my favorite biggame rifle cartidge for many of my own reasons. For me it offer the best combination of what I need for the game I hunt. Plus I've spend years adjusting and fine tuning my own handloads to my own specs and now that I'm there I just got to lazy to do the same with any other cartridge.
Ask yourself....have you ever been exposed to the recoil of a biggame cartridge such as that of the .270 or .30-06?? Not meant to offend, but.... Can you handle the recoil to be able to shoot either of these well?? The answer to this question will play a lot into how accurate either of these cartridges can be for you. Only you can determine that.
To conclude I will tell you what my experience has been with these two cartridges. They are both superbly accurate rounds with both solid reputations and excellent track records spanning decades. While the .30-06 may have been used much more within competition match circles, both have taken more biggame across North America over the last century than most people even realize.