My main rig for a few years was ITX... Silverstone RVZ01, really nicely sized case with very good GPU cooling, could easily go in a small suitcase for when I travelled between my parents place and college. Unfortunately the CPU cooling side for most ITX cases of that size is difficult, the 120mm AIO I initially used dried enough to be unusable in around 18 month since I had twisted the tubes a bit too tight to make it fit. The air cooler alternatives were unsatisfactory for the 4790k with the overclock I wanted to run, so I ended up just tossing it in an ATX case once I settled down at my own place. If you need the portability or don't have the space though, there are quite a lot of interesting ITX options around nowadays, especially the last year I finally found some that I felt offered enough space advantage to actually be relevant without sacrificing too much cooling.
