There is nothing wrong with test phenylprop. It is a test with half life about 3-4 days. It basically falls between prop and cyp. There is nothing about it that makes it better of worse than cyp or prop. Testosterone enanthate doesn't have the stacking syndrome as Deca because test converts to many compounds including estrogen, DHT etc besides its renal and hepatic clearance. Besides more frequent injections you really don't get any more benefit than cyp. When using cyp at more than 200mg a week I always recommend doing more frequent injections anyways.
My recommendation is always to choose a test ester based on the fastest acting ester you have in your cycle. So if you are using tren ace and plan to pin daily, you might as well use testosterone prop or even better acetate. If you are using NPP where you are injecting three times a week you can use cyp and just divide weekly dosage by three. Hope that makes sense.