I can explain why "I" think it came out #1. But just to get the data straight: The 270Win was not picked by the majority - no cartridges on the list were - it was picked by the largest plurality where around 20% of the folks say it is their favorite. So...this means that for about 80%, the majority, it was not their favorite.
We have to remember it was a Favorite pick not "the best for a specific purpose" pick, although, both can be true.
I can see it coming out on top for several reasons: 1. It is adequate to more than adequate for the majority of hunting the voters do. 2. It has been around and getting the job done for over a century. 3. A lot of the voters likely grew up with a 270 in their household (dad, uncle, grandpa, cousin, friends) and got one themselves - ands liked it. 4. The majority of the voters are likely avid deer hunters, who take the occasional elk or other larger game, and it has always worked. 5. It has relatively low recoil when compared to guns flinging heavier projectiles - faster. 6. They read a lot of O'Conner and enjoyed the romance in his prose regarding the 270. 7. They prefer not to have a magnum. 8. They prefer not to have a short action. And this list can go on and on.
But most of what I said above could be used to justify picking many of the other cartridges, just substitute the names and tweak the verbiage.
My absolute favorite daily driver here in the TX brush country is a 1995 Jeep YJ 5 speed with only a canvas shade most of the summer - a cab in the winter. Its not even the best Jeep I have - my Gladiator is. However, it can get everything I need done and it is my absolute favorite to drive around here.
I have a couple of 270s mixed in my pile of guns. One is my old Sako, with whom I have a great deal of history with and love, while the other is a recently purchased Ruger African that I have no history and love for, but I really enjoy tinkering with. Both are VERY good shooters.
I was fortunate enough to retire "relatively" young from the military and other than when it is super hot as it is now, I take a long gun to the field 2-3 times a week. I might just spend a few hour walking and stalking or sniping a stray rock across a mesquite flat or plinking one of several steel targets I have placed here and there. My favorite guns for this are relatively compact 20-22" barreled rifles, that are not heavy, and I usually run a short, ultralight can. I also hunt with these exact same guns. Last year I went through a little over 700 rounds hunting and doing my walks. I'd say 75% the time I have one of my 308s, the other 25% is a mixture of '06, 270, 243, 45-70, 44Mag carbine.
For normal killing, at traditional ranges, on NA game (deer, antelope, elk), I find there isn't a nickel's worth of difference between the 308, 270, and '06. My first Africa hunt was last year. The 308 took a zebra, a blesbuck, and an impala - all DRT. The '06 took a kudu, wildebeest, zebra, a waterbuck, and 2 impala - all DRT. My '06 and 308 both were shooting the same weight bullets, with the difference of about 100fps and my shots were 225yds and in. No animal can tell the difference. I firmly believe if I'd taken my 270 with my hot loaded 150gr A-Frames, it would have killed with the same authority.
My personal favorite for 99% of what I do - Ruger Hawkeye Hunter .308 Win, 20"barrel, ultralight can, 1-6 LPVO, 165gr bullets running 2700-2750 - I adjust the bullet (A-Frame, Sierra SBT) based on what I'm doing. But....I'm happy with any of the others.