I'd say to go with the higher protein. I'd say "always" but there's probably some exception that kills the rule! In any case, protein's what cats need; the lower calories usually come at the cost of higher carbs and that essentially means empty calories.Would it be best to go with the original since it has the highest protein value or the indoor since it has fewer calories but a lower protein value? (45% vs. 38%).
It sounds like you've tried a ton of food but I'm trying to think of what else Petsmart has that might be good to try. Aha! Yesterday I went there to pick up some Nutro Natural Choice (canned), which our cats really love. It's a favorite even among picky cats. Maybe Snowball would like it? It's definitely a little more expensive than Sheba but the calories are likely higher -- it's a fairly filling food, at least for our cats. And carbs should be pretty low. Nutro's selection isn't always especially stable but it might be worth a try if they happen to have it.
No matter what, good luck!