Non-Realistic can have the benefit of looking “good”, well, it can have a timeless art style if you’re able to establish a good one. Take the example of The Legend of Zelda: The Wind Waker and Twilight Princess. Wind Waker looks amazing still, Twilight Princess… well, not a as nice.
With a smaller team and a lower budget, stylized art can be much more attainable. Look at Telltale Games, they are able to push out about 10 episodes over at least 2 games in a year.
It also comes down to… what are you good at? Are you good at stylized art styles? Are you good at realistic art styles. When to comes to Terrain there are great products like World Machine which can get you started generating terrains pretty quickly, and when it comes to foliage, there’s SpeedTree, which, you can get a monthly subscription for specifically for UE4 for a mere $19/month, and you only need to pay that while you want to use it, once your done making trees and vegetation for a while, you can just cancel your subscription and keep using the assets you generated, and if you need to make trees again… just resubscribe.