Like with the Quakers', Mennonite "churches" may not be apart of any national conference or denomination and as such accurate estimates are hard make. Listed below are the conferences/denominations that do have a nation presence or are estimations for the congregations/churches at large.
Amish Churches: Founded in the 1720's, membership is estimated to be around 400,910 in over 3,038 Districts (2024). There is no central headquarters of the Amish so a website with a description was included instead.
Beachy Amish Mennonite Churches: Founded in 1927, membership is estimated to be around13,000 across 201 churches (2012).
Church Communities International(Bruderhof): Founded in 1920, membership is estimated to be around 2,203 across 19 congregations (2020).
Church of God in Christ, Mennonite: Founded in 1859, membership is estimated to be 25,897 across 170 churches (2020).
Conservative Mennonite Conference (Rosedale Network): Founded in 1910, membership is estimated to be around 16,493 across 109 churches (2020).
EVANA (Evangelical Anabaptists): Founded in 2015, estimated membership is unknown across 42 congregations (2024).
Fellowship of Evangelical Churches: Founded in 1865, membership is estimated to be around 9,000 in 65 churches (2012).
Hutterian Brethern: Founded in the 1530's, membership is estimated to be around 40,000 in 400 colonies (2016).
Mennonite Church USA: Founded in 2001, membership is estimated to be around 71,058 across 550 churches (2020).
Missionary Church: Founded in 1969, membership is estimated to be around 57,638 across 463 churches (2020).
US Mennonite Brethren Churches (Mennonite Brethren, US Conference): Founded in 1878, membership is estimated to be 43,308 across 218 congregations (2020).
There is no official bible for these denominations, but different churches may prefer one translation over another.
Holy Bible : Containing the Old and New Testaments: Authorized King James Version