This very much depends on what I’m carrying, where I’m going, what the weather is like, and my outfit - and yes, all of these change every day! 
Day to day I have a leather tote handbag from Amazon which I use, it can hold my MacBook Adorable (work machine), 10.5" iPad Pro (goes most places with me), my Bose QC35II, AirPods (for commuting), work ID/access card/keys, lunch, and whatever else I decide to carry around.
Some days I use a Kipling backpack instead, it has enough padding to make sure the laptop/iPad aren’t uncomfortable, and holds about the same amount.
You’ll notice both of these bags are not full of pockets and sections - I find that leads to me losing things or thinking I’ve lost things which is not fun.
For longer trips/taking my new 15" MacBook Pro around I have a cheap backpack from Amazon - purchased because it said it could hold a 15" laptop, and because the pocket structure didn’t look too overwhelming. I’m actually very pleased with it, and the USB port for connecting to a battery pack inside is used more than I expected it to be. I have this back in a nice blue and unless it’s stuffed it looks smaller than it actually is - useful when flying!
In my bag I always have a small mesh pouch which came in a set of 3 from Ikea, (the small square one, not the pencil case shaped one). This has a USB to lightning cable, a USB to micro USB cable, a small USB wall plug, and battery pack with a watch charging puck built in, this often saves the day and lets me keep going when betas zap my battery.