It's actually depends on what your goals are.
If you strictly care about gaining size, we recommend just straight weight lifting.
However, for the average individual who wants strength, size, and athleticism we recommend a combination of weights and calisthenics.
What exactly do you mean by a combination?
Here is our recommendation:
1) Use weights for leg workouts.
As we previously discussed, calisthenics is at a disadvantage when it comes to leg training. Ditch the one legged squats and perform weighted back squats, lunges and deadlifts instead!
2) Use weights and calisthenics for upper body exercises
One of the benefits of incorporating both is that you get more exercises to choose from. Instead of being limited to barbell bench press and dumbbell bench press, now you can also incorporate push-ups, ring push-ups , dips and ring dips to your regiment.
Being able to choose from more exercises has two benefits.
firstly, it allows your body to constantly have to adapt. This prevents plateaus and allows your body to constantly improve.
Second, it allows you from being bored from just doing the same exercises all the time. And the constant improvement and PRs will be you motivated to keep training.
3) Use weights for isolation exercises.
As we previously discussed, calisthenics is at a disadvantage when it comes to isolation. Use weights machines and cables for your delts, bicep, tricep hamstrings and squads!
4) Use calisthenics for warm-ups
Calisthenics are closed-chain movements. They are much safer. When your body isn't warmed up, its at a higher risk on injury. so use calisthenics to warm up safely! Warm up for the bench press by doing push-ups! A side benefit of doing this is that you won't be hogging up the bench too long if you get your warm-up done by doing push-ups.
5) Use calisthenics when you don't have access to the gym.
Don't have access to a gym on your vacation? Don't want to get an expensive 1-day gym pass to a gym thats a 30minute commute away? Do a quick outdoor calisthenics workout while basking in the sunshine so you have more time to do the fun vacation activities you came to do!