If it's just for more convenience in building a custom setup with liquid then obviously look at Caselabs, but they are very expensive. They are big with liquid cooling and custom setups.
Off the top of my head there is the Fractal Design Define S without the drive trays so there is lots of room for liquid cooling. Same build as the Define R5 minus the drive trays so it's $50 cheaper.
Then there are the cube cases where the power supply goes behind the motherboard. Corsair has the 540, Thermaltake has a few.
Then there are reverse cases. The windowed side is on the right so the video card gets reversed so the heatsink is facing up and not down. Corsair makes one.
Pretty much any high end case will be accessible. Lian Li, NZXT, Fractal Design, Caselabs, Corsair, Coolermaster, Phantek, Deepcool, Zalman, etc.... There is lots to choose from.
Nowadays people use a single SSD and 1 large hard drive. It's rare to see 5 hard drives in a system. I am a fan of an external drive for storage and an SSD boot drive. Or the SSD and a NAS server for storage. I have 2 computers, tablets, smartphones, Xbox One, media players, televisions, blue ray players, stereos, alarm clock, etc... that all stream files direct from a single NAS. Cheaper then having drives for each computer and leaving them turned on 24/7 to share and stream. People also do not instal CD-Roms unless you burn or you actually need it. I prefer an external burner and plug it in the odd time to do an install or burn.
All that being said you can remove your drive trays and open up the inside of the case and have tons of room for liquid. And all the cases have tons of grommets to pass wires to the back side of the motherboard tray. They are simple to work on. Cases are well built now and there are many that would suit your needs. But seing as you want lots of room and you want it easy to work on check out mid towers, full towers, and cube style double wides. Anything smaller will be congested.