If you are to go vegan, it requires that a little bit more thought be put into what you eat. Just because someone is vegan doesn't mean they eat healthy.
I think that besides maybe certain things that can be genetic, what one does on a day to day basis is important to take into account.
What do I do? Eat a lot of carbs to be honest.
Beans and rice
Kale, spinach, broccoli, brussel sprouts.
I tend to go for high nutrient foods. Those up there make up the staple of my diet. I eat fruit as they are in season. I love pomegranates. I suppose I also eat a lot of a avocados.
I am not very scientific about I eat.
Last Christmas fast I went vegan keto. I don't recommend doing this, I had no idea what I was getting into. Definitely not a sustainable diet.
Last Lent I ate nothing but bread(it was sprouted bread though, which is really nutritious). My wife thought I was trying to starve myself to death, so halfway into it I compromised and agreed to eat any veggies she would put between my bread.
Lent for us starts Monday, and I will be touring monasteries to find one to settle in(my wife is dead, so I intend on becoming a monk). I will eat whatever they have for me to eat there.
Monks tend to eat vegetarian, and they are some of the healthiest people you can find.