For gestalt, I like to group whatever classes I cant decide on by their primary mental stat.
Like Factotum, wizard, archivist, erudite, warblade, beguiler, etc... for int
Crusader, sorcerer, bard, binder... etc... for cha
druid, cleric, ardent, (archivist), (arcane)swordsage etc.. for wis
Then consider a few options,
Pair an active class, it's powerful abilities use actions(a full caster for example), with a passive class, it's powerful abilities do not use actions in combat(incarnum classes, dragon shaman auras, artificer crafting, factotum goes here too b/c it actually give you more actions)
Choose two classes for synergy, such as cleric//druid and focus on summoning, or binder//archivist, there is a vestige that grants a crafting feat(you can swap this out daily), now the artificer doesn't have to focus as much on say golems.
There is also choosing a main class, then using the onther side to supplement its weaknesses, dipping for example; but, you don't have that option.
That being said, the most powerful is probably going to be factotum//something int based
Then it just comes down to what you want to play, from what you listed I would recommend:
druid//cleric, swordsage or totemist:
Factotum//warblade or artificer(meleeficer)
Or crusader//binder, sorcerer or bard