Howdy and welcome.
That depends a LOT on your bike and circumstances. Do you want to quick-lock it when out for a coffee, or leave it outdoors in a city where the neighbors' cars are sometimes found up on concrete blocks in the morning?
I'm sure you'll get lots of suggestions once we know your bike model, where you live, where you ride and how you store your bike. I use an ABUS folding lock for quick-locking the MiniST2 on the spur of the moment, but also carry a very sturdy ABUS U-lock and cable strapped to the rear basket for locking to a tree or if I want a bit more security. I live in a small town in the woods, by the way, and my bike is in a locked garage at night; crooks don't fare well around here, but I like to be prepared.
This stuff combined is quite heavy, but on an e-bike that's not noticeable to me.