Isolation

[akak]

Say you're playing with someone who limp/calls pretty much every hand and calls down with any piece of the flop and sometimes worse. His c-bet folding % is like 25% let's say. He also frequently bluffs when he senses weakness. You have position on him and get a decent but not great hand like Q9s.

Is it better to limp behind said player, keep the SPR ratio higher, and value bet him to death if you hit, thus saving yourself money when you miss? OR is it better to make your standard pfr, isolate him, and again value bet if you hit?

I know this is probably very vague, and the correct answer is "it depends", but do your best to answer. I can make arguments either way, so I'm really not sure. Thoughts?