I had several versions of the Motorola Droids a few years ago. I liked them, but they were glitchy. I swithed over to the Samsung Galaxy S3 when it came out. I loved it, and it was 100% reliable. I kept it for about a year until I broke the screen too bad then I got another S3. It was just as good. My wife bought me an S4 for my birthday. It was the only phone I have ever kept past my 2yr contract. It never had one gltch the whole time I had it, and I'm not easy on my phones. I actually cracked the screen about a year into it, but I just kept using it because I liked it. I finally changed over to an old S5 we had as a spare because I dropped the S4 again destroying the screen. I like the S5, and that is what I use now. So, I have had two S3s, an S4 and now an S5 without ANY glitches or slow downs like the Motorolas used to have. They have great cameras and screen resolutions. I want the S7, and I believe the S7 has an SD card slot which I like.
My wife has an S6 Edge +, and I'm not really a fan of that one. It's just too big and the Edge doesn't fit a case well. It functions flawlessly though.