During Ramadhaan the Tabligh Jamaat people canvass for spending the days in tabligh.

Answer

Tablighis have become extremely deviant. They lack ikhlaas, and compound this great deficiency with ignorance, hence they fabricate corrupt beliefs and bid'ah practices. It is extremely vile to believe that their innovated methodology of 'tabligh' is superior to the Masnoon I'tikaaf of Ramadhaan.

While it is not reprehensible to abstain from the Masnoon I'tikaaf, it is haraam to believe that the tablighi jamaat method is more rewardable. Only Allah Ta'ala knows which act is more rerwardable. This depends on circumstances and only Allah Ta'ala can judge the issue of Thawaab (reward).

The ghulu (haraam extremism) of the tablighis threatens to make the Jamaat a bid'ati cult such as the Barelwis. In fact, they believe that spending months at their respective markazes is superior to even Hajj. Such a notion is dangerous for Imaan. While it is possible for a person to receive more thawaab for perhaps assisting a Muslim in hardship than a person who goes for Hajj, it will be vile to claim that charity/sadqah is more rewardable than Hajj. In a given situation one act, be it Nafl, may have more thawaab than even Hajj or even Jihad. But such knowledge is exclusive with Allah Ta'ala. It is not permissible to compare one act with another deed and to issue a categorical ruling regarding the superiority of a specific deed of virtue.

When the bounds of the Shariah are exceeded then one enters into the domain of haraam ghulu. The Qur'aan Majeed states:

"These are the limits of Allah. Whoever transgresses the limits of Allah has indeed oppressed himself."