To be honest, my favourite part of 3.x was the number of options and choices. Even if you just have the phb you have a ton of options and build potentials in each class.
My least favourite part was that most of those options made you fall behind, and many of them were brokenly overpowered. While the options in the current 5e playtest are far from that varied, most of the non-spell caster ones just give you ways to waste 1d6 damage each round.