You could only play one build at a time. The innate versatility of classes in play were very close - comparable numbers of skills, powers, feats, wealth/level resources, same retraining options - prettymuch all Tier 3. The wizard, with the option to prep an alternative to each daily or utility, and a few free known (but not free to cast) rituals was surely "high" in that Tier. Essentials started back in the direction of Tiers, giving Mages more prep options, and curtailing the versatility of other classes, especially martial, (and arguably producing some dysfunctional sub-classes, while 'orphaning' the RunePriest & Seeker) but to nowhere near the extent 5e.