I use a Conbee II dongle with deCONZ for all my Zigbee stuff, and try to use Zigbee wherever possible.
The Hue bulbs are great, and also act as repeaters, so I have those sprinkled throughout the house. But they're expensive, so I used Sengled bulbs for most of my fixtures. The Sengleds are endpoint-only, though. So I mix those two bulbs to keep the mesh dense but also save some money.
All my door sensors are the SmartThings units. I use a mix of SmartThings and IKEA Trådfri motion sensors. One SmartThings water leak detector in the basement, a SmartThings button, and a Trådfri 5-button remote.
I started this just to have a convenient way to control lights. My house is really old, and almost all lighting is table- and floor-lamps that I would have to walk around and turn on and off. Or ceiling lamps with pull cords.
But after getting into Home Assistant, I started going a little nuts with the automations.
My favorite one: A month ago I was getting ready for bed when I realized I left my oven on all day long. For 12 hours it was keeping the oven at 375˚F. But then I realized that I already have a motion sensor in the kitchen, and if I just moved it to the door of the oven, the built-in temperature sensor could be used to remind me that the oven was left on. So now I have a rule in my automations.yaml: If the kitchen temperature exceeds the living room temperature by more than 10˚F for more than an hour, send a notification to my phone that I left the oven on.