Short rest all the way. To be honest, I kind of hate long rest abilities. It’s really difficult as a player to predict how many encounters there are going to be in any given day, which makes it a nightmare to try to manage your daily resources. If you blow through them all early and it turns out there’s still a lot more to go, you screw yourself, but if you try to conserve them and it turns out there was only one encounter that day, they go to waste.
With short rest abilities, you can generally count on being able to use them in most encounters, unless it’s clear you’re in a position where you can’t spare an hour. It’s significantly easier to predict when you can afford to spend them and when you need to conserve them. If I had to pick just one or the other, it would definitely be short rest, but Ideally, you’d have a mix of both. Mostly short rest abilities that are your bread and butter for most encounters, and a couple of big long rest abilities that you save for when you need a Hail Mary.
I think 4e really nailed this, but I get that every class having the same structure felt too samey for many. I think Essentials was very close to finding the sweet spot, with some classes being more reliant on at-will abilities with a few Encounter and Daily, and others being more Daily heavy with fewer Encounter and weaker at-wills. They tried to do this with 5e as well, but it didn’t work as well. I think that’s due in large part to short rests changing to an hour instead of 5 minutes, making short rest abilities less reliable and more dependent on the DM.