Where to purchase, does it matter?

After struggling with my GS5 for the past year due to:

-inability to clear storage due to mysterious Miscellaneous files taking up 2GB though I clear most and the top one is 49 MB
-pictures taking 10 seconds to snap
-phone freezing
-fast battery drain
-having to re-move my apps to the SD card every time there is an update. One at a time. This is the most frustrating thing about this device (hope it isn't so on the Edge)

I have searched and addressed what I can but I'm done with this phone and am most likely getting the Edge 7 (had a galaxy phone since the first one - Captivate)

That being said, I was wondering if it makes a difference where I purchase. I'm ATT and I'm new to the Next plan, which is what they all are. And I'm eligible for an upgrade obviously. Target, Best Buy, ATT store...does it make a difference? I know they each have perks from time to time...but that notwithstanding, I'm guessing my bill will all be the same depending on which Next plan I choose...that's a constant, right?

Any leanings towards any store (or even online through ATT for that matter) amongst you guys? Or...

does it not matter.

I know I'm asking a pretty obvious question but wanted to make sure I covered my bases. I'm not sure which Next plan to do, if I can swing a down payment, that'd be better. Not sure if that varies as 'perks' either between the stores.

Thanks in advance,

John