If you are going to TM it then Bullet Seed may be a better option - it is a better moveset unless it is a neutral opponent.
For the majority of things you will use a SoB Egg for, it is preferable to have Bullet Seed.
If it is a dual psychic moveset, then yes Extrasensory > ZH
CAVEAT - ZH is legacy and has the potential to change in the future to be stronger again - just something worth considering.