If don't know if you have any experience with Android so I'm not sure how much advice would be overkill. I guess my basic advice that was passed along to me that's worth passing along to you is to stick to the App Store and Samsung store and Amazon for apps. Even then, read user reviews and comments. Stick to apps from respected names. My husband has been a developer and knows how to squash all kinds of problems so he is more adventurous about downloading apps. As a result he has downloaded a few that look legit but will launch a pop up ad on you even when you're in the middle of using another app. It's almost like being infected with a virus. I've dealt with pop up ads in Apple apps too, but only when I had the app open. In Android apps sometimes run in the background and you won't even know it until something causes a noticeable problem. Like when Pokémon Go was interfering with the Samsung camera app.
If you're looking at LG, the upcoming LG V30 has a beautiful design and specs. From what I know of reading about it, LG lags in customer service, support, and providing updates. They demonstrate a desire to learn and upgrade their products and services so we may see an improvement with the release of the V30 but it's still an unknown quantity. The V30 is expected to cater to and excel in video recording, with advanced stereo audio options as well as prosumer level camera control and features. Still photos may not be quite as good as offered by Samsung and Apple, but they offer a very unique wide angle camera in their dual camera system that takes great landscape photos. I have heard their selfie camera is weak.
The release of the LG V6 was marred by ridiculous regional differences that favored the Asian market and practically insulted the western market, especially Europe. The V30 release is not expected to repeat that mistake.
Last year's HTC 10 offered me the absolute best pure phone connectivity I've ever experienced, but was prone to overheating and teardowns reveal a lazy, poorly thought out and executed internal design. They waste internal space and make bulky phones. Their current version of Android is light and HTC permits rooting and custom roms without voiding the warranty as of last year, but double check that for this year on their site. I avoided them this year due to the reported fragility of the glass phones. They have interesting features and a reportedly good camera but they don't hold their value at all. I'd advise waiting to see what Google has them do for the Pixel line. I've not needed their customer service but their warranty has generous terms. They were good at providing updates to my unlocked phone purchased directly from them.
There is way too much for me to say about Samsung and this post is already too long. In brief, I dislike how the curved display on my S8+ causes distortions at the edges and I get too many reflections no matter how I angle the phone. Note 8 would probably be the one to get since it takes what is good about the S8+ and refines it-- or so I am reading, I do not own one. Its also more powerful and faster, I think its generous alotmemt of ram helps. It's expensive but deals can be found. Samsung customer service is a mixed bag in the USA.
I don't have many insights into the Google Pixel to offer, unfortunately.