I have a CHIP, PocketCHIP, RPIs (not sure how many) both 1 and 2 (no 3s yet), 2 Pine64s, a CubieBoard4, and a Banana Pi. I love all of them, but they serve different purposes. RPis are great because the GPU is at least somewhat usable, and getting more useful all the time, its the only one that isn't based on an Allwinner SoC, which is great because Allwinner isn't really friendly to open source. For me, Pis are good because they really are the easiest to work with and most readily flexible, they can do media stuff orders of magnitude better than any others thanks to the partial opensourcing of the video core stuff.
CHIPs on the other hand, are a different animal. They are not going to be doing media stuff (most likely) since they are allwinner chips with mali gpus. However, CHIPs have some really nice advantages. They have onboard flash, so no need for buying sd cards, but that also makes it harder to install what you want on them (they are my only non-gentoo devices right now). They have built in wireless stuff which can be neat (but no ethernet). but for me, the best part is the white little two pin connector which is for a 3.7v lipo battery, CHIPs have a built in charging circuit (as does the pine64), which, combined with the built-in wireless, and smaller form factor, makes the chip way more portable than rpi, which is really awesome for some projects.
Thats what I got to say at least. both have their merits, but also their problems.