Hard to choose. I've been looking at several of those, the r4/5, enthoo pro and the be quiet 800. I might have gone for the 800 but no side window (finally have a decent looking build so wouldn't mind a windowed case this time around). I like the options and how well thought out the enthoo pro is, especially since it comes with a psu cover standard (with the windowed version) rather than making it a separate purchase and the fact the case pretty much comes completely apart (if you ever needed full access for deep cleaning, painting etc.) rather than riveted. Tough to choose at that point really. Personally I've pretty much settled on the enthoo pro for the reasons listed above and I like that the usb ports are front mounted rather than top mounted. Dust is inevitable and I'd rather not have it settling into my usb ports. Before considering that and taking a long hard look my previous consideration was the r4 blackout.
Can't really say it's the best case for everyone especially since looks play an important role and everyone's taste is different - but given the $100 price, don't see anything beating the enthoo at that level. I like all those cases, even the 800 - just wish it wasn't lacking a window. A lot of people don't like windows, but I like the clean lines and look of the enthoo and r series from define. They pulled off having a 'minimalist' window without looking like a carnival show. Not every windowed case has to be fitted with 10+ enermax tb vegas quads trying to give someone an epileptic seizure lol.