Lets pretend they raised the level cap to 24 (not saying they will or wishing for it, just a 'what if'). What would you believe your play style's best build would be? Lets say max level for any one class is 20 as a level increase to 24 would likely be a larger promotion to multiclass toons. Lets not only hear the build but the reason why you'd take that route.
I personally would go with elven monk 18/ranger 6. Mostly due with tier 4 stance, decent bonuses to 2 favored enemies (evil outsiders and likely constructs as another) As well as getting tempest 1/ninja spy 3(when it releases...this is a dream thread after all lol.) The hp would be moderate (mid 500s maybe low 600.) But fort and reflex saves would both be base +14, will +11 (not counting the epic save progression which for lvl 24 I think is +2 to all saves.)