I've had my Turbo for less than a week but I'm already positively smitten with the battery life and overall pep of the phone.
My old S3 had such lag issues that, towards the end, I often could not send a text message without waiting up to 5 seconds between typing each letter. Sounds ridiculous and it honestly was. Unplugging my S3 in the morning at 6 am meant that I had to charge it again by noon to keep it from dying. Then charge it again when driving home. Then again overnight. I ended up carrying around a spare battery AND a battery charger whenever I knew I'd be away from home for more than a couple hours.
When I finally was looking at new phones recently, I considered the S6 but, in the end, battery life and not having to deal with TouchWiz made the Turbo my top choice. I don't see the S6 or M9 as significantly better than the Turbo in any way. S6 processor is octocore, sure that's awesome, but let's get serious, is there anything that you throw at your Turbo on a daily basis that causes your phone to lag or wish you had an even faster processor? I don't but maybe I'm not as much of a hardcore user as others. Corporate push email, personal email, streaming audio and video, the occasional game of Zelda on an NES emulator (I'm not a hardcore gamer, still love my 80s games), photos, web browsing, and some social media are what I use my phone for and that hasn't changed in years (basically same stuff I've been doing on my phone since the original Droid Incredible was in my pocket). To be able to do all of that and not worry about lag or battery issues, I couldn't be happier.
Now ask me again at this time next year and we'll see if I still feel the same.