I have a 22" monitor. I do NOT maximize my browser window. I like to have easier access to the shortcuts on the left side of the desktop. And I often have a WMP window open playing a video, so I use a reduced size browser window.
What do you use? 
Why are you confused? People like what they like. Some people have 30 tabs open all the time. I close mine as I go and use history if I need to go back to something. Everyone browses differently and for different reasons. Videos for me mostly come from the browser so they’ll just be in a tab unless I break another window out, and I prefer to keep attention on the video so will usually maximize that while I’m watching it, too. But that’s me and my preferences are different.
My monitor is 14" and I always maximize the browser. Old computer, I can’t play online videos anymore and can’t open more than 10 tabs or so at a time.
I use a reduced size browser window. My eyes get sore if I have to do a lot of left to right movement, so especially for sites like this, that use the full width of the browser window, I prefer to reduce the window size and have the text wrap.
I have a 24’’ monitor , I don’t to minimized unless I am doing some photoshop and watching a movie at the same time I like the viewing space
I always maximize my browser window. My tower pc’s at home and work have dual monitors. The browser is open on one of them. Even on my laptop the browser is full screen.
I have two 27" monitors.
I keep my browser windows at about 75% of the width of one monitor.
Maximized - but then, I’m also a dual-monitor user (23")
My laptop has a 15" screen. I generally maximise windows and have 60 tabs at once, I half the screen when I want to watch something and do something else at the same time.
At home, I keep my browser at around 80-90% of the maximum (for access to shortcuts on the desktop, for instance) unless I’m watching a video. At work I’m always bringing other windows to the top by clicking on them (Outlook, Excel, Word, whatever) and I keep them all at around 50% of maximum.
I maximize mine. Seems weird not to but that’s probably me being old and imprinted with memories of 12" screens where you needed it maximized to see what the heck you were reading anyway.
I rarely maximize anything. Slide shows and movies, that’s about it. OK, large spreadsheets sometimes, I guess.
I always maximize the window unless I need two windows open to compare or something.
Always maximized. If I’m doing anything else at the same time all it takes is a simple click on the shortcut in the taskbar to open that program.
I have my music running in the background, and leave a space on the left (Media Go from Sony) so that I can see what is playing and even read the lyrics.
No need to maximize the browser. At work I have a pair of 30" monitors and at home it is a single 24’ monitor.
I keep mine at 6 inches by 9 inches. I like the evenness of it.
Dual monitors but browser windows I keep with 1/8 inch all around. Old habit/preference from needing max size on small monitors but easy to grab & slide over. I still do that a lot for various things.
I maximize, and then make the text substantially bigger than normal. If I put a Word document at 100% next to my browser window, the text in my browser right now is equivalent to 24-pt font. If only I could do the same in every application. My eyes are not what they used to be.
Nobody, has mentioned Alt-Tab yet?
You guys and ladies are slipping.
Alt-Tab is all you need to open windows hidden behind your browser or windows that you sent to the task bar. Alt-Tab also lets you select the desktop. Full screen windows are never a problem when you use Alt-Tab
Window key- E opens file explorer
Window Key - R opens the run box