plots = RegionPlot3D[#, {Q1, 0, 1/2}, {Q2, 0, 1/3}, {Q3, 0, 1/4}] & /@ 
      {j1, j0 && MUB, j0 && Choi};

    coords = Cases[#, GraphicsComplex[x_,__] :> Median/@Transpose[x], All][[1]]& /@ plots;
    labels = {"PPT", "MUB", "CHOI"};
    texts3d = Graphics3D[MapThread[Text, {labels, coords}], Axes -> True];

    Show[plots, texts3d, 
      AxesLabel -> {Subscript[Q, 1], Subscript[Q, 2], Subscript[Q, 3]}]

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/AckPl.png