I always Glass Cannon the Tank, thats the best party member to do it to, they have so many HEalth anyway.
Actually cure wounds is better than a healing potion at higher levels but is not as good as the other high level heals. It regenerates so can be used over and over potions cant, has a (really) short range so it can be used on others but isnt great for that and costs nothing in gold. On the downside it does cost more AP, has a long cooldown, has a short range, and isnt as good as the other heals at higher levels.
Hm, how much will it heal later? Right now it's healing 155, which is same as a potion, however, a potion only costs 3 AP instead of 6. You could take two potions for that AP... heal 312HP instead.
Potions aren't very expensive. You only need level 1(or 2 at most) pickpocket to steal minor heal potion, and you can get like 100 of those throughout Cyseal alone! At level 3 crafting, you combine 2 minor heal to make 1 big heal for 155HP. So, basically, they're pretty cheap! You can even buy them from soldiers every time you level up if you want, if your barter is high and once you've got some Rep for more discounts.