This is a GREAT conversation with a ton of good information. I think as with anything each person is slightly different so your needs and preferences will be different. Here is my story.I have shot several deer with the 25-06 and a lot more with the 243. With good bullets placed well they work very well. I use them now mostly on antlerless hunts when I can take my time and pick broadside shots. Even at 250 to 350 yards they do very well. I've had good luck with Sierra Gamekings and Nosler Accubonds in both. The Accubonds are tougher and penetrate deeper, they are hard to beat. The Sierra's fly great and put deer down fast with a good hit. Somewhat surprisingly I have seen better penetration a lot of times with the 85gr Sierra HPBT from the 243 than the 100gr Gameking softpoint from either. In the 25-06 the 100gr Swift Sirocco 2 intrigues me. It is a tough bullet with a great BC for a 100gr 25 cal. I tend to shoot Sierras more in these rifles because I bought a lot of factory seconds and use them for varmints and predators as well as game.
I tend to lean toward other rifles for buck hunts. I like a bullet of around 140 grains with a high BC and SD that penetrates well and bucks wind great. I want to have confidence in taking shot angles that might not be perfect, and breaking shoulders when necessary. I've used the 270 and 270 WSM, 7mm Rem Mag, 300 win mag (with 180gr bullets), and my favorite the 264 win mag. I am currently trading for a 6.5 Creedmoor to see how I like the 6.5 diameter in a shorter, handier rifle with less velocity.
For your deer gun I'd ask if you plan to shoot longer range and dial elevation with your scope. If the answer is yes I would probably go with a 6.5 Creedmoor, 260 Remington, or 7mm-08. You can get a bullet like the 140gr Accubond that will do a great job on deer. In my 6.5 Creed I will first try the 143gr ELD-X. I don't expect it to be as tough as the Accubond, but I'm not sure at 6.5 Creedmoor speeds it will need to be.
One thing to keep in mind, the 6.5 Creedmoor doesn't benefit much from a long barrel from all the tests I have seen. I went with a Browning Hells Canyon Speed when I got mine ordered due to the 22" barrel on that model. I don't think you gain a lot with more barrel, I'd really prefer a 20". That rifle had the best combo of features I personally wanted.
If you don't plan to dial elevation the 25-06 is really hard to beat with a tough bullet. The 110gr Accubond or 100gr Sirocco would be my top picks if I was planning to use a 25-06 as my primary deer rifle. I've seen that 110 Accubond hold up well to a shoulder of a big buck at 80 yards started at over 3400fps from a 257 Weatherby. I think the Sirocco is at least as tough. Those can be pushed hard enough to be really flat shooting out past 300 yards making wind and elevation corrections easier.
I agree with the 6.5CM. I have been shooting a 6.5CM before they were cool. It had to do with weight for me. I was shooting a 300WSM for over a decade. However as I got older, weight was starting to become a factor.
So I went down to a 6.5CM in the Savage lightweight hunter, 22" barrel as well. In the first few years I struggled to find a factory ammo that would shoot well out of it. I think the barrel was so short I was not getting a consistent powder burn. I found a fast burning powder and increased the weight of the bullet. That seemed to work. I now shoot the Hornady Precision Hunter 143gr ELD-X bullets. I have yet to lose a deer or antelope. It's a winning combination. I hope my experience helps you out. Good luck in your quest! ~Ike