About CHD I agree to disagree, it's not about reputation and rarity, it's about professional encoder teams that are working daily to deliver all kind of HD content in the very best resolutions and quality. You can find from simple 720p to full Bluray almost every encode of theirs and they also have an encoding team for mobile devices as PC tablets called CHDPad and that means a lot for only one tracker. All CHD encodes worked flawlessly for me on my laptop or TV with perfect clarity and sound.
Besides that, they have a serious staff that is not begging for money, their donation system works only from 40$ and you don't have too many privileges for that, only big amounts can get you invites and double BP only(and believe me that many users donated to the site). Another advantage is the three language system CHD has, I don't know about TTG, but you can't find that on HDWing. They also have big activity on english forums, good encoding tutorials, recruitment thread for other trackers, etc.

Regarding rarity, until 2 years ago finding a CHD invite was very easy, but give the user a finger and he will take your whole hand. As an example they opened these days the invite system again so it's not really a big deal getting in.

The biggest plus in the past for HDWing was the encodes, they used to be the first team to upload new HD movies waited by many.

I had World war Z Wiki release in 720p and I can say that at the minute 71 or something like that my server blocked and my laptop froze and not only once, I tried the 2nd and 3rd time thinking that serviio was going crazy, but it was the file.