Good guns. I personally am not a fan of a single shot though. If that buck comes through chasing a doe I want to be able to pop off a few rounds.
What makes you think its the flattest traveling round?
25-06 is a good choice, but I prefer more energy.
I won't say its a terrible cartridge, but definitely highly over rated. One plus is the wide variety of factory loads available for it.
I personally will never use one for any kind of deer hunting. If a marginal shot is made, I want more power than a .270 has to offer. Of course if you always hit them where you are supposed to, the deer won't run 100 yards even with a .243. But the thing is shit happens. Not many people can make perfect shots at 200 yards or on running deer. Sometimes your scope may be off.. Sometimes you may hit a limb. Etc, etc.
I'd highly recommend a Tikka T3 Lite in .300WSM. Thats my current deer rifle and my favorite out of any gun I have ever shot. Comes with a Sako barrel, is 1.5-2lbs less than other .300s, and guaranteed MOA accuracy out of the box. The recoil is not near as bad as you'd think it'd be either. I could shoot it all day long. I shoot hand loaded 165 grain Nosler Partitions out of mine. Can cut the same hole at 100 yards.
The main thing is to hold several guns, shoot some if you can, and choose whatever YOU feel is best.
I shot a 30-06 from the time I was 10 until I was 17. Excellent caliber also. As someone previously mentioned, the .308 is like its little brother. Both calibers have a shit ton of great factory loads available.