You can't really go wrong with plants and Bettas, they love them all. Yes some plants are easier to care for but that's for you to decide. Most aquatic plants are pretty easy anyways, if the water conditions are good enough for the fish (clean, temperature, light, etc.) it's good enough for them.
If you really want to make it fun for your Betta, add a variety of plants of different shapes and heights. Bettas love exploring and the more variety they have, the more fun they have too. As for "favorites" each Betta is different, some like to rest on wider leaves and some like to rest between 'grassy' plant blades, and some underneath leaves.
Try different kinds and you'll see what he prefers, you can start with the ones you find prettiest, just make sure the leaves have no sharp edges or spikes and won't dammage your Bettas delicate fins.
So far mine have loved every single one I've tried.
Have fun watching your Betta playing with his new plants!