A real personal choice. Just like helmets and tyres. One lock does not suit all.
Some carry a D lock, half the weight of their bike. Personally I carry a home made 3mm stainless steel wire which is 2m long.
It will go round a post and frame, my seat, bags and wheels. I would call it a cafe lock. Easy to cut with bolt croppers, quite a bit harder with wire cutters.
I am often told on forums I will get my bike stolen using this wire. The bikes are insured and in 55 years of cycling I have been lucky enough not to lose a bike.... yet 🍀😁
I use a decent lock with the wire and it is usually fastened to jannies bike with a combination cable.
It works for me.