I have a new HAF 932 Advanced case, and found that its got less looking in terms of FANS then my CoolerMaster HAF XM does.

What's the best side panel fans to use? 230mm or should I go with 4 120mm's and figure out how to hook them all up? Any idea's? Trying to get the temps down on my 2 1080 Ti's that are on my Asus Maximus VII hero Z97

Bigger the better.
 
Moves more air and runs slower which means less noise.

Back in my day we didn't mind the Delta fans sounding like a jet fighter taking off. I personally don't care for a slight noise but now days run things pretty silent.  Really bigger fans are better as they can move more air in less rotations resulting in good cooling and near silent operation. While some fans are better then others keep an eye out for the noise to how much air it is really pushing. It seems like you can hit a point where a fan can be a lot louder for not much real world gain. 

Squall_Rinoa86
I have a new HAF 932 Advanced case, and found that its got less looking in terms of FANS then my CoolerMaster HAF XM does.

What's the best side panel fans to use? 230mm or should I go with 4 120mm's and figure out how to hook them all up? Any idea's? Trying to get the temps down on my 2 1080 Ti's that are on my Asus Maximus VII hero Z97

 
So I'm guessing this is going on the removable side of the case panels.  Best way to run these assuming you have four fans is use is to probably have a simple fan controller modded into the side panel so that there is only one cable to disconnect when you have to remove the side panel.  Something like THIS would be an example of a fan controller that should be simple enough to mod into a side panel and run the fans.  Turn them up when needed or throttle them down when they are not.  You would just remove the controller from the bracket and use the bracket as a template on where to drill holes for mounting.
 
If you are looking to drive PWMs and have the mobo control them then run an extension PWM cable from the mobo to the hinged side of the panel.  The have a 4-way PWM splitter mounted to the panel allowing a simple and accessible disconnect point for when you have to remove the panel.
 
Again the point of both options above are to allow for a simple single and accessible point to disconnect the fans in the event you need to remove the panel.  Be sure to pick up some small zip ties and some of those 3M adhesive zip tie mounts to keep the cables tidy on the panel.
 
I'm not as familiar with fans as other members are but hopefully these examples will give you some ideas how to set them up on the side panel so they don't become a nuisance when you need to take it off.
 
As far as running Deltas... don't.  Not really worth the noise unless you have a good high AMP programmable controller.  Some of those deltas eat a lot of power and most controllers are not really meant to run them plus they are not optimized for acoustics.  Some models even have oversized motors that create a rather large dead space if you were to ever plan on running them directly on a radiator or heatsink.  They are basically server grade fans.  Great, reliable, and a solid built tank of a fan that can move air but not the greatest for a small room that you are working in.  I have used them in the past but they are pretty much retired now lol.