I think one of the major factors in the popularity of the salafi da'wah is the lack of a better alternative in many places. Things I have witnessed in *some*, not all, sufi-oriented 'ulama that turn me and many others away from them: Some of the famous sufi shuyukh seem to either openly or tacitly approve repressive regimes, are lax in practicing outward sunan or at times even belittle them (I've seen personally a number of big sufi scholars who are clean shaven or have a five-o-clock shadow and wear suits and I've seen scholars belittling and mocking people who have long beards and keep their garments about the ankles), encourage dhikr with dancing, musical instruments, and calling upon deceased awliya for help (they certainly are not without precedent but many educated Muslims are turned off by such practices), ghulu in praising their shuyukh (including having huge posters of a shaykh in a masjid in the direction of the qiblah), crypto shiism (attacking Mu'awiya, doing tafdil of 'Ali (ra) over the Shaykhayn (ra)) etc. Salafis, despite having many faults, come across as very sincere and their da'wah is very simple and makes perfect sense on the surface. Who doesn't want to return to the Qur'an and sunnah and abandon bid'ah?