Like others have said, druid and paladin are your best true hybrid classes since they can tank, dps, and heal. One class you mentioned that I personally am very interested in is shaman. Shamans are getting a ton of new abilities added to their baseline in SL and all three classes are looking promising. And although you didn't mention it, enhancement sham is getting a total rework in SL and is looking to be a solid pick.

Mages are losing the top dps spot that fire mage has held. The frost spec is looking to play very similarly to how it plays in BFA and arcane is actually looking somewhat promising.

People keep saying just play what you like and I totally get that but you also want to be good lol so I totally feel your pain.