Fullbody x3 per week is awesome for 'getting back to it' in the early stages but later on, once you have built up to heavier loads and are training at higher intensity levels, you just won't be able to sustain enough intensity for the whole session well.
PPL is a good simple alternative, although IMO I think if you are looking for hypertrophy as a main goal then when training a body part once a week only you need to training with higher volume. The study data, and my own personal anecdote, is that when volume equated (same number of work sets with the same load/intensity through the week in each condition), splitting your work into 2-3 sessions for each body part per week leads to greater growth than just doing all your sets once per week in a single larger session.
The only way a once a week frequency might not lag behind is if you do more work in total in that single weekly session than you would if you trained over two or more sessions per week. Basically that means, for hypertrophy at least, once a week training offers less hypertrophy per volume of work.
One way around it is a split I sometimes do and have helped a few others set up that has everything trained twice per week but using only three workout sessions.
Monday - legs, push
Wednesday - push, pull
Friday - legs, pull
Six-eight exercises total per session using mostly compound exercises. Reps ranged from 6 to 12 depending on the exercise, number of sets dependent upon individual recuperative ability.
