Fun thread.
For me, it's wallet, phone and wrist watch 99% of the time when I leave the house.
The car will start via and app, so if I'm driving, I'm about 50/50 on whether I take the car key or not. (I know, I know, kinda risky)
We have smart locks for the house and I don't have the faintest idea where my physical house keys are.
My wallet is a small card holder, usually with ~4 cards in it and occasionally a few folded bills that don't make it any more bulky. I tend to use Apple pay or pay through apps when available, so I've been leaving my wallet in the car more often or leaving the house without it altogether. When I have it, it's thankfully thin enough to comfortably fit in my back pocket.
My naked, uncased iPhone is always with me and usually in the other back pocket. As mentioned, it's partly my method of payment, but also my mobile office, my alarm clock, my calendar, my photo album, etc... oh, and I tend to talk on it quite a bit
I like to think of myself as a horology enthusiast and have acquired some very nice timepieces over the years. I wear a watch 99% of the time when I'm out of the house and about 50% of the time while at home or at my desk (home/only office). The watch I'm using will be on my wrist, next to me on my desk or kept in my watch box with the others.