Mathematically, these three roots are equally valid. If there is a reason to prefer one over the other two, it must come from some understanding of the of the meaning behind the mathematics. For example, in problems which have solutions from quadratic forms, it is frequently the case that there is a negative solution with no valid physical meaning, and it is discarded.
In[1]:= NSolve[Pi - x - 1.2*Sin[x] == 0, x, Reals, 15]
Out[1]= {{x -> 2.11485436221882}, {x -> 3.14159265358979}, {x ->
4.16833094496076}}
In[2]:= Plot[Pi - x - 1.2*Sin[x], {x, 0, 2 Pi}]
