Coming from a person with 34 years of experience in this field, who has been trained in air flow management, it seems everyone is missing some points in building a rig.
1. Every component is different.
Even if they are the same type of component, this includes cases you must take them as being different if you re trying to be as efficient as possible in your airflow cooling management.
I've had to swap out same brand cooling fans because I was getting an unusual result in a certain part of a case.
2. Every build is different.
Even buying the same components for multiple rigs can get you different results in cooling. I've seen this happen too often to state otherwise.
3. YOU MUST KNOW all of the strengths and weakness of all of your components that you use in your build.
The perfect example is my MSI X570 A-PRO motherboard and how almost every major tuber craped on it because of hot MOSFED issues. Well yes that will happen if you are going to drop in a R9 5950 and overclock it. That is not what this motherboard is made for and I saw it's potential. For $125.00 out the door, you can beat that price. It now has a 5900OEM (before that a 3600) with its ram and Video card undervolted. It runs very cool and for my CPU cooler is... wait for it.... a Hyper T2... Yup a Hyper T2 instead of a big hunk of metal in the case.
I rig this rig 16 hours a day 7 days a week coming on 3 years. I am not beating my rig to death by overheating and saving my money by not buying expensive water cooling setups. These savings will be rolled over to my next setup or an upgrade on my video card.
Now all of my data on this rig has been posted previously, but I just did a quick shot with MWM on my temps as of this posting. Again 2 Artic 140mm fans side case. 1 120mm fan in the back. The PSU has been flipped to provide extra pushing out of air from the case and the Hyper T2 fan has been rotated 90 degrees to help pull air from the outside.
View attachment 272296
4. Again as stated before. To get the best cooling possible you MUST take the time and patience to fine tune your rig to achieve the best results.
This means knowing all to components outcomings, knowing which type of fan/case/cooling setup to be used and finally taking the time to to swap out parts to make the rig to run as cool as possible. It takes a long, long, time to fine tune your rig. And yes I do use a small fogger to track my air flow. If I get lazy then it is a"Punk" (a fire starter on a stick is called a punk) and eye balled the smoke with a flashlight. To fine tune this the first time it took me 2.5 hours which is why not many people do this anymore.
They just buy the components, slap it together and call it a day.
Now concerning the Water/Air thing. That's your choice and I can't tell you what you want in your rig.
However from my perspective and the dozen or so water cooling rigs that I had to clean, you will never EVER see me with a water based set up, because IMHO water set ups deteriorate over time... in certain cases of neglect badly. You must do general maintenance every year to get the best performance from water cooling. Air cooling... heh replace a fan if it goes bad in 5 or so years and blow out your case of dust every 3 months, which you have to do with a water based cooling method anyhow.
Again regardless if you go water or air. IMHO,... If you do not take the time to fine tune your air flow/cooling management, you are just asking for problems down the road.