Im curious on how most value a good defensive catcher.

I have a catcher 90 def great arm threw out about 40% of runners last season. He hit slash line of like 240/280/310

then I have a guy who is gonna hit 270-280 maybe 20-30 hrs but will throw out maybe 20% of runners and def rating of like 38...

I'm not sure what you mean by "def rating" but this is a game of plus/minus.

It's all about what you value most. If I'm an AL team, I don't mind using a defensive SS and C because I have 7 other spots to get my runs. Unless, of course, I don't have a hitter at one of those 7. If you have 3 non-hitters in your line-up, you're essentially giving up 3 innings per game.

In the NL, you've got the pitcher's spot and any other non-hitters. Since I value SS defense over any other positional D, my catchers in the NL tend to be offensive players.

Why not both? In the NL I like to have a heavy hitting catcher with no D and then have a defensive catcher that can come in for innings 7-9 when we are ahead.

I value pitch calling over anything else

Also consider park factor. I got away with using a 47 PC catcher for a few seasons in an NL pitchers' park because he was either first or second on my team in OPS during that time and the team was also top three in OAV and WHIP, bottom three in batting. Won a few division championships with that setup.
A great defensive, no-bat catcher would have taken away a significant amount of what little offense I had, and my pitching staff was already performing beyond its expectations.

I personally prefer strong defensive catchers on my teams. Sometimes you may have to platoon, but generally you can find a mediocre hitting catcher with fantastic pitch calling and defense. You can almost always get them and rule 5. If I'm trading a good asset, I always look to get one thrown in as well. I think the majority of the owners favor good hitting catchers so this is usually not a problem.

Great information ! I appreciate everyone

Okay, I can understand that viewpoint, so here's my question: We know the truly great hitting catcher is a rare bird. I agree with your DiTR theory, it does generate great defensive catchers, but are the +++ Arm and Pitch Calling defenders THAT numerous? I see a lot of great pitch calling with only average arms.
I think we're all agreed, you want a catcher who's outstanding at either offense or defense. But most of us are stuck deciding whether it's better to go with only half-great offense or half-great defense.

Did you do your own RC value ?

Stats, batting, extended.

I didn't read all of pjf's post but he's very opinionated and always right(just ask him). Take that for what it's worth.

It was years ago but I ran about 20 seasons of data, my catchers only, and found that 10 points PC was worth about .12 ERA. So it would have to be 40 points difference(a 50 vs a 90) to be approximately half a run of ERA.

I wasn't posting to say you were wrong(didn't read all that because you are a bit long-winded). But the OP is relatively new and may not know that bad advice posted as an absolute isn't uncommon in this forum. I felt he needed that info.

@damag these concepts don't only apply to elite fielders vs elite hitters, it's ok to use these same metrics using any two examples for comparison to decide which is better between the half-good options. Typically the defensive choice is better because you'll always need a better hitting option than you think

I actually can't argue with this viewpoint at all because it's the exact logic I use for all the other positions. I very happily run glove-only shortstops and CFs on both my teams, and draft glove-only players over useless AA caliber hitters. But then I suppose that pigeonholes me into looking for a little added offense from my catcher if possible, because I know I won't get it from my SS and CF. And playing in pitcher's parks, as I said, gives me the leeway to do so.

If I played in a hitter's park and drafted on the side of offense, then hell yes I'd be looking for a 80/80/90 Catcher.