The debate over what is considered a more halachically acceptable, or even just permitted, hair covering for women has been raging for decades. It is sharply debated especially in Israel where the culture is less formal and it is far more acceptable for women to wear tichels outside, even at work, than it is in countries like the USA and Europe, whereas in many places in the Diaspora women feel they have more of a need for the sheitel and the appearance of hair that it provides, so the issue is less at the forefront.

According to an "alon" (ie a parsha paper, of sorts), quoting from a new sefer being printed, Rav Chaim Kanievsky has paskened that a sheitel is [sometimes] better (ie more appropriate according to halacha) than a mitpachat, or tichel, for a woman to wear as a hair covering. Rav Kanievsky says it is better, or can be better, because the sheitel generally covers all the hair, whereas a tichel often does not. Rav Kanievsky qualifies that by saying that the sheitel must be obviously a wig in appearance, but if one looking at it cannot tell that it is a wig than it is prohibited. Rav Kanievsky adds that all the gedolei Lita followed this opinion and their wives wore sheitels.

 (so you have a blog quoting a website quoting an alon quoting a sefer quoting Rav Chaim Kanievsky. so, as always, don't base your actions and halachic decisions on a fifth hand quote on the Internet. If you have any halachic questions, speak to your rabbi rather than basing on anything quoted on the Internet)

I would only point out that it is well known that many of the gedolei Lita had wives who did not cover their hair at all. As well, maybe they felt they had to being in Chutz Laaretz and needing to look like hair, while had they lived in Eretz Yisrael at the time perhaps they would have worn other hair coverings.

The alon also quotes the sefer in the name of the Chazon Ish saying that a wig/sheitel is better than a tichel even if it is not so clearly obvious that it is a sheitel and it looks like real hair.
source: Kikar

Being that there is no big chiddush stated here, I am a bit surprised that this is newsworthy. While I personally did not know Rav Chaim Kanievsky's opinion, though his wife wore a sheitel, as does his daughter -so perhaps I assumed it - it seems like nobody knew his opinion on this matter until the sefer came out and revealed it. Has nobody ever asked him before?