With regard to 8x42 vs. 8x32 the main things to take into account are usually exit pupil (ease of use), fov (size of image, via afov), and weight. If you wear/don't wear glasses the ER may be critical:-
For me, ER 15 or 16 is usually enough with glasses but have gathered that this depends how much ER is used up by particular eyepiece surrounds so that others have, with certain models, reported problems around this threshold. (At least with Meopta's 12x50 '15' was fine ).
On the other hand, without glasses, sometimes people find that the eyepieces cannot be pulled up far enough!
In those respects, for me with glasses, 8x32 has at first seemed to be most suitable, but I have usually then wanted more magnification. Looking still at 32mm this has had most impact on ER and ease of use, while with 42mm or 50mm the increased weight became an advantage.