I know that this will give the California haters more ammo but, here the use of plugs by a second party is prohibited. Owners can do what they want but repairs by tire shops or mechanics cannot.
I've used all three methods and only had one problem and that was when a plug was used and I think the hole was too big for a plug alone.
I'm to old to do repairs now but if I were to carry one or the other I'd go with the combined plug/patch. In fact I may just buy three sets of them one for the DW and myself and one for each DD. If a flat occurs in a remote area a respondent may not have either and at least we could offer our own.