What about NZXT Guardian 921 it comes with three 120mm fans preinstalled , 120/140mm fan optional for the top ,its cheaper than the Gigabyte one that I listed which is like 9k & this is like 7600rs & it got a screen on it which shows temperatures & does it matter if the casing is Mid-tower or full tower ?
It does matter indeed. With full tower you have a lot of space between pc components so heat get blown and dissipated much better especially if you put more components in your pc like extra hard disk or two, in mid-tower spacing is issue as components are usually packed tight to the walls and their is just not enough room for both processor and gpu to blow off the heat effectively especially if both are running air coolers.
So again if your main concern is about best possible ventilation inside your casing then you should be looking at Full tower. HAF 932 is an extremely famous casing and very highly regarded amongst gamers, it doesn't look the prettiest but its almost second to none when it comes to ventilation. As a matter of fact, HAF stands for "High Air Flow" so basically its designed specifically for that purpose.
Finally remember that casing is a one time investment so it may look expensive at first but It will serve you a very long time unlike your processor/motherboard which you will probably exchange after 3-4 years max. I have my casing for almost 7-8 years now and with bit of caring, monthly blower routines and its still in like new condition with 0 dent or anything and while I have changed my processor/motherboard more then 3 times during this period, my case is still going strong and can easily endure another 8 years unless I get tired of it somehow and decide to change which I probably won't.