Getting 3.3 (V) from a 5(V) rail - Emitter Follower, or something else?
Why not an LDO (Low Drop-Out) regulator? They're easy to use: capacitor on the input, and one on the output, and have much better performance than any zener circuit, load regulation-wise and line regulation-wise.

The TC1269 (just a random pick) has a 2.5 % output voltage accuracy, can supply 300 mA, and has dropout voltage of maximum 160 mV at 100 mA. Dissipation will be less than a shunt regulator as well.

The TC1269 is only 31 cents in 1s at Digikey. A zener + transistor may cost as much.

Digikey lists 3600 types which can supply at least 100 mA.

If you really want a voltage follower then remember that the output voltage is about 0.7 V ( the base-emitter junction voltage drop) lower than the base voltage, so you'll want a 4 V zener to get 3.3 V out.