Best phone - Tie between my G2 and current G5. The G2 was amazing for its time and aged fairly well. By the end of 2015 it was starting to bog down a bit but was still pretty great. Around January the bottom of the screen started having touch input problems and I started shopping for a new phone. I was torn between the G5 and S7. At the end of the day, I just don't like Samsung's phones anymore. The G5 is fantastic and has one of the best (phone) cameras I've ever used. Battery life is good and it's very snappy/fast in day to day use. I love the rear power button and wish it still had the volume buttons back there too.
Worst Phone - Galaxy Nexus. I upgraded from my Droid Incredible hoping it would be... incredible. It was about 2 months before I decided I hated it. It was slow, had crappy battery life, and the camera was barely mediocre. It was a lesson learned that just because it says "galaxy" or "nexus" doesn't mean it's a good, frequently updated device. F- you verizon for that quagmire.
Best/Worst Tablet - If it weren't for the touch issues, my Nexus 7 2013. It was a great little performer in a fantastic body at a very, very good price. But since it had touch issues almost from day 1, I couldn't ever grow to love it. Some days it worked flawlessly... others, I want to crush it with a hammer.
I dropped it and killed the screen this last Thanksgiving. I almost got another one when a few people on here suggested the Nvidia Shield K1. $200 for a much better tablet from Nvidia?! Sweet! It really is a good tablet for $200.... however... it suffers from a known issue with Wifi connectivity. It's rage inducing sometimes. It'll have issues connecting to wifi or staying connected, randomly dropping for no reason whatsoever. Sometimes it connects but certain apps wont be able to access their servers. For example, Netflix won't be able to load a video (or even its menu) due to "connectivity issues" but Speedtest.net says I'm getting 12ms ping and 50mbit download. HBO will work. Sometimes it's the opposite, netflix wont but HBO will. (at the same time, several times, I tried both on the same wifi with my phone or laptop without issues)
Anywho... I'm starting to think a high/decent quality tablet for a low/decent price gets to that price by skipping QC control altogether...