I have an s3 and am eligible for an upgrade. I am fine with my s3.. I have it rooted and it works well w/Gear 2 watch and I have a lot of accessories for it, so aside from being jealous of new technology, I don't need to upgrade. So, should I wait until the next phone or make the jump and grab the s5?
I am the weird android lover with stacks of phones. However, I was late to get the S5 and S5 Sport. Based on side by side specs of the Nexus 6 (compared due to being the latest), I would have to say the say the S5 wins big for me at least.
Little things are missing on the Nexus 6 such as the IR remote which I love in my S5 even though most people do not know it is there.
I like my 'Seek' FLIR camera which is great on the S devices, but not on Nexus. (Predator Vision). I use it for house repair and animal detection in walls.
The lacking of size and SD card hurts when in a combo. I love my other Nexus devices, but today I tend to fill my space all the way up due in part from work and part from movies/apps. The S5 can handle a 128gb micro SD. The sprint nexus is only 32gb. No 64 offered yet.
I forget if the 6 has one, but previous models were missing the FM antenna. The S5 has one.
MHL out is nice on the S5. But really a chromecast takes care of that issue for the Nexus.
For my wife controlling text messages from the phone via the tablet is important and supported with the S5 and S 10.5. We like the traditional messing app over hangouts.
All other things compare to me primarily since I place custom software on my phones. If I were a regular user maybe my choice would be different due to 'sense' overlay on the samsung.
Biggest secondary issue for me beyond specs was price. The Nexus 6 is now $250 upgrade on Sprint. The S5 is $50 online at Amazon and then matched by Best Buy. There is also a deal for the Sport or regular S5 for a lease of $0 down and $20 a month with a $15 dollar refund each month. Thats $120 for the phone and nice for those tight on money at the moment, but you must turn it in. It compares if you think about the process of selling it used to get the next phone. Plus, at Best Buy they wave the $36 sprint connection fee for the lease. When I bought my S5 and S5 Sport I got a $50 gift card from Best Buy as well. I then sold my two S4's for $85 and $95 on gazelle. Plus, I got the 5% Best Buys rewards. And I selected the Amazon card offer on gazelle getting me another 5%. In sort I got paid to take the S5.
If you can wait the S6 is around the corner. I am not saying it is worth waiting for, but it will make the S5 cost even less.
Good luck to you.
Dave