I strongly prefer a lock back.  I have had a modern liner lock come open in my pocket and have had frame locks partially open when dropped.  Neither experience instilled a lot of faith. 

Yeah I think i know what you mean, if you're talking about  those spring assisted tactical  liner-locks.  If they don't come with a safety-latch forget about it.  

But if you're talking about liner-lock knives such as   a Case Russlock or the Rough Rider locking Sodbuster then there is no worries about accidental blade deployment.  These knives still have a slippy back spring which keeps the blade closed.  The liner lock only keeps the blade open.

Every knife is different. That said, I still fall on the lock back side of the survey.

Liner locks like the Russlock are a different animal all together.  They are a basic slip joint with the addition of a line lock.

Modern liner locks are only held closed by side pressure for the lock and a detent.  There's not a whole lot holding them closed.

Ain't no way I'd carry a spring assisted knife unsheathed.  I'm not that trusting.