IMO, every build should be multiclass, with two levels of a "mix" class.
For examples:
18 Wizard / 2 rogue
18 Sorc / 2 paladin
18 rogue / 2 fighter
18 bard / 2 rogue
18 monk / 2 Fighter
18 ranger / 2 monk
18 cleric / 2 rogue
18 FvS / 2 fighter
18 paladin / 2 rogue
18 fighter / 2 paladin
18 barbarian / 2 fighter
Just my opinion.