Clip on:
Pro: Cheap, can be carried on when buying new glasses
Con: you have to carry it separately, depending on the "system" (clamp, magnetic) they might Not be fitting when buying new glasses
Extra glasses (with correction)
Pro: Its Just the Same as the normal glasses but with sun protection
Con: you have to carry it separately, when eyesight Changes you need new ones
Sunglasses you can wear over your normal glasses:
Pro: relatively Cheap
Con: you have to carry it separately, bulky, only fits when you have relatively small normal glasses
Transition:
Pro: you only have one pair Con: they normally dont Work when driving a car because windshield Filters Most UV (which triggers the darkening of the glasses)
First three are First Hand experience from me. Never Had Transitions because i mostly need sunglasses when driving.
Oh ok. I Had written them off after learning they dont Work (20 years ago or so)
My Favorite approach to the Problem is extra sunglasses. Most opticians Here now offer a free 2nd pair when buying a new Set of glasses and i make IT sunglasses then.