2000+ calories is what you will need for even a moderately active day in the woods. 3000 when it is cold.

How you get the total number of calories does not matter as much as getting them, although its probably better to have some of each.

In cold weather, you probably should get more of your calories from fat, and less from carbs.

Protein is probably the least critical part of your meal in a bad situation, at least for a few days.

The reality is that the meals many hikers claim to be living on when on the trail are well below starvation levels for the amount of energy expended. They do OK and so will you for a short period of time taking in fewer calories than you are expending.

IMO, food during a short term survival situation approaches being more a comfort item than a necessity. However, I see nothing wrong with being comfortable.

Whether or not a Snickers or a Mars bar is an ideal survival food is a totally academic point for me. Where I live, The heat would just turn them into a chocolate goo 6 months out of the year. Do Cliff bars hold up in high temperatures?

I've been trying Kashi TLC ("Tender LIttle Chewy") granola bars that I have scored at Costco. 140 calories each but 45 of those are from fat (5 grams including 0.5 saturated). 19 grams of carbohydrates and 7 grams of protein. They taste good but don't seem to stay fresh and chewy as long as I'd like -- only about a month. Also kinda bulky for a survival food.

One of the virtues of Cliff Bars, most varieties, is that they only get mildly sticky in the highest of temps. That combined with very tough, tear resistant packaging, makes them very good inhabitants of the bottom of your pack until they are needed. No goo

Jif Extra Crunchy Peanut Butter: 16g fat, 7g carbohydrate, 7g protein.

Cheap, simple, convenient. I try not to over-think such things. As has been pointed out, for a couple of day's emergency rations, pretty much any calories you like and will eat when under stress will do.

PB has long been my back-up fuel of choice for backpacking, so I have confidence borne of experience that it will sustain my under heavy exertion if I "misunderestimate" my rations or ETA, and that it is palatable to me. I hoard the PB packets from MREs, or load my own.