For the absolute best long term no fuss tubing, I would recommend EPDM tubing, like EKWBs ZMT (zero maintenance tubing). But it is black only.

If you want coloured or clear, I have used hardware store tubing. But I was accepting the possibility that it might go wrong and I might have to do some serious cleaning or change coolants. Also, I only used it where it couldn’t be seen so that if it turned colour it wouldn’t matter.

Silent Base 801 from BeQuiet! I would actually not recommend getting this case, definitely get the Silent Base 802 if this look appeals to you. This case does not have great thermals, and on the 802 they fixed a lot of the problems from what I've heard.