The type of journaling that is most beneficial to you really depends on you and what you are trying to get out of journaling, and the reason you are journaling.
One popular type of journaling that can have many benefits is gratitude journaling, it's also one of the simplest to do. At the very least, all you need to do is to write down a few things that you are grateful for. This alone can help you better put things into perspective, especially if thinking about things you are grateful for is a difficult task, this can really help improve that.
This, of course, can be built upon. You can start by writing down just a few things that you are grateful for, and then you can also write down the reasons why you are grateful for them. As you progress, you may notice that you are able to find more things that you are grateful for, and that finding these things gets easier and easier. This can have a positive impact on your life, causing you to have a more positive attitude and a better understanding towards life, people, and yourself.