It depends on your taste.
JJK is more of a fast paced traditional battle manga. Great art work, the fight composition and sequences are top notch. It's easy to catch up to. But it needs to be read carefully as the ability exposition and power system are hard to follow at times. What you look for in characters and plot is up to you, so I'll leave that up to you.
Chainsawman is definitely an easy read. It's unique, random and wild as hell when it comes to narrative and characters. Different tone from most of what's in Jump atm.