Former bike commute workshop leader and bike shop employee. Across the board, I’d recommend either any onguard lock (they are the cheaper version of kypronite, which is pretty much the best) and my general rec is $10 on the lock for every $100 you spend on your bike, up to $1000… The shorter the u-lock, the safer it is (no room for a crowbar) but harder it is if you have aluminum (larger) tubes or less standard bike racks.
Abus is my favorite folding locks, which are better than cable loops and also nice and foldie and better if you don’t have access to standard bike racks all the time - you can use them by themselves or with a U-Lock. They are what everyone in Berlin used.
Protip: if you lock your rear wheel inside the rear triangle of your frame, you’ve also effectively locked your frame!