Am I a better candidate for hand Sclerotherapy or fillers? (photos)

In the first picture your hand and fingers are extended and no significant veins are visible.  Fillers can temporarily restore volume to the hand but they are not a long term solution.  In the photo with your hand down you have prominent veins.  Those are normal functioning veins but if desired for cosmetic reasons, they can be treated with sclerotherapy and or a microphlebectomy.

The left hand does not show hand veins very well.  The best pictures are with the hands down below your waist.  The right hand has significant veins and I would treat the larger vein with endovenous laser and the smaller veins with sclerotherapy.  I cannot comment on the left hand because I do not see any vein.  Once the hand veins are treated, if you want to increase the volume of your hands then a filler would be indicated.  A filler is a temporary solution for loss of volume but treating the hand veins is a long term solution for the veins.