Antiglare coating is a must for me. There’s a reason it’s used on lenses in cameras; it enhances contrast, and for purely aesthetic reasons, makes it easier for others to see your eyes, making you look better.
High index plastic is also great IMO, it significantly reduces the thickness and weight of the lenses. Also aesthetically, it reduces the distortion of the sides of your face when someone’s looking at you. It is not the hardest material available, and I believe the higher the index, the less hard they are. My lenses are typically completely scratch free for a year or two, getting only minor scratches after that.
I’ve never had an issue with coatings. I clean my glasses with hot water and Kimwipes (laboratory lint free wipes). I don’t use any lens cleaners or any other cleaning products. I never dry wipe my lenses.