You could use E for the first half of cycle and transition to P so that exogenous test clears faster and pct can start sooner. That is if you have both and want to use them up.
Test E is plenty stable at once or twice a week. It is also more soluble so the brews can be higher concentration and have less pip.
Test P is a pain: More PIP and usually lower concentrations so, larger injection volumes to get the same dose.