At this writing, Wikistats lists 287 Wikipedias, while Sitematrix lists 288. Wikistats seems to be excluding the Maithili Wikipedia. (I believe this Wikipedia has been live since November 2014.)
wrong project - fixing
Meanwhile mai.wikipedia is in the table. has been added a while ago.
at this writing 288 wikis in wikistats ... but now 290 in sitematrix
also see T64739
added "lrc" and "gom"
now 290 in both tables