I use IslamToday, Islamqa, Fatwaonline, Fatwaislam, IslamWeb.
Islamtoday answers back really fast. They are Alhamdulilah good trustworthy [knowledgeable] scholars.
I would reccomend them [esp for response to answers]
Islamqa has a very big fatwa 'archive', Alhamdulilah. I've sent a few questions, and I didn't receive a response, Allahu Alam maybe they already had the answer posted. But the Sheikh is Alhamdulilah on the Quran and Sunnah, and is straightforward with any answer. May Allah preserve him, ameen
FatwaIslam and FatwaOnline are both great sites, they however do not accept new questions (Allahu Alam), but are more like archives of old and new fatawaa from the greater scholars (i.e. ibn baz, uthaaimeen, albani, etc rahimuhuhullah).
IslamWeb accepts new questions, and they are also on the Quran and Sunnah Walhamdulilah,
Usually those are the ones I visit,
Hope that helps.
Wa'alaykum Asalaam Wa Rahmatullah