Things I like:
OnePlus: Nothing. I enjoyed the OnePlus One. They shat all over OnePlus Two and OnePlus X users with software updates. Have no respect for them and wouldn't buy another device from them. Lots of 3/3T people are watching them VERY closely for software support over the next 12-24 months.
HTC: their designs and audio game. HTC is one of my favorite old 4 bands (along with Nokia, Moto and Sony; RIM gets an honorary mention here). HTC was my first smartphone so I always want them to do well and stop getting in their own way. Shout to the folks who know about HTC Manila.
Samsung: Nothing. Been there, done that. Only modern Samsung I came close to buying was a Note 5. I like their hardware a TON but I'd pick EMUI over TouchWiz/Grace UX/Samsung Experience all day. Much respect to the Galaxy S2 - the phone that let people know they were serious about Android.
LG: dual cams and audio. I like that thickness of the G6 (*cough* Libra *cough*). Dislike the bootloops. Would I buy a V20 over the Mi Note 2 as a do-over? It would have been the last carrier branded phone I'd buy when it was on sale for $320 including tax.
Nokia: dunno. They are like BB now so we will see. When I want Nokia as I remember, I yearn for a N-series (shout-out to those who used these) or a Lumia 925.
Huawei: hardware. I still say MIUI>EMUI>Samsung for my taste software wise.
BB: like the looks of the KeyOne. Battery and design is in my wheelhouse, along with the keyboard. I'm one of those who doesn't use Swype, so going back to a physical keyboard would be a shorter learning curve.
Moto: stock-ish software and design. But Moto hasn't made a top tier camera since before the X line. And they've shat over some phone owners (my former Moto Maxx/Droid Turbo people understand). I like the Z because it's different and I can get a Qi back. Otherwise, I'm watching them closely too.
Xiaomi: good value for money. They need to get their head out of their butts and into Eruope seriously in the next two years. MIUI is a heavy *** skin though. Need to see what they do with that over the next two years.
Apple: nothing. Been there, done that. Only phones they've made since I sold my iPhone 4 (their best design ever with the OG iPhone the second best) I'd consider are the SE and the iPhone 7. Don't need the app fatigue - that's why I left. 10(!) years to get a file manager? iTunes still as prevalent as ever? C'MON man!
MSFT? Check my screen name out to see what they're doing in the phone market.
Does this work for you?