Bard/Sorc full support PvP.
Bard/Wiz full support PvE.
As someone with both at 55, this guy is pretty spot on. Bard/Sorc is significantly better in PVP, Bard/Wiz is a bit better in PVE. Don't listen to the people who swear up and down that one is far superior to the other at anything, those are just people trying to justify their subclass choices.
It's worth note that Bard/Sorc is almost always the preferred choice even in a PVE party that does not otherwise have a main Sorc or higher level sub Sorc, but that's pretty rare and Bard/Wiz definitely outshines it in cases where they are present. I also prefer Bard/Sorc for dungeon soloing simply because it actually has single target damage.
It might sound like Bard/Sorc is clearly better, but it relies on what the rest of your party looks like in order to make full use of its skillset, whereas Bard/Wiz can join any party and perform as well as it always does. If you usually play with a group of friends and none of them are main Sorcs or expected to be higher level than you, then Sorc is a pretty safe pick for both PVP and PVE. If you're joining random parties then Bard/Wiz is a lot more versatile when it comes to the type of parties it can perform best in.
Pick which skillset you like more basically.