They are generally secure. Any hack on them has never gotten clear text passwords.
LastPass seems to be the one who gets hacked the most and I use that term very lightly because it's usually just user emails
Which don't get me wrong is bad because then you can be at Target of spearfishing but you should not shy away from using a password manager because at the end of the day if you use it correctly it's going to be more secure than whatever you're doing now
If that was your concern you wouldn't be going on a public exchange then