You have some good choices to choose from, but I find it impossible to say that any of these would be the most important thing for a herp store. The number one, absolutely, most important thing I look for in a herp store is the apparent health of the animals - ALL of the animals. If there is one animal that even hints of being ill, I would not buy there.

This is why I have not bought more than one reptile or amphibian in a herp shop in the last 10 years or so that I can remember!

Remember that most herps take a long while to show obvious signs of disease, so if it is obvious that a reptile or amphibian is sickly, they certainly have not cared for the animal for way too long as far as I am concerned.
After that there are a lot of other concerns. If the enclosures are not clean or at least look as if they are cleaned regularly, I would not buy. I have seen tanks with one poop in there, ok - maybe no one had time to get to it yet. On the other hand, I have also seen shops with tanks that have three or four poops inside, some in the water dish, and some smeared all over the glass

. I leave places like that quickly.
Knowledgeable employees are a great plus although, an unknowledgeable one may not always send me running. One that tells me I don't do snakes, well that is another story. Any shop should hire only people who will handle all of the animals. Why would you hire someone in a pet shop who would only handle turtles when you specialize in all types of herps? Yeah, he/she may be a turtle expert, but how could an owner allow an employee to snub customers like that? That would likely be an out the door express for me. Of course, that same person (mentioned in someone else’s post) could have easily said: "Sir, do you mind taking it out. You see even though I work here I am not a really good snake person, so otherwise you will have to wait or come back later when someone else is here." It is a shame that customer service no longer includes common sense or common courtesy.
The size of the store does not matter too much. One of the best herp shops I ever visited was also the smallest herp shop I have ever been inside. It was called Fang & Claw and was located on West 14th Street in Manhattan in New York City. This was a long time ago I guess in the late sixties or early seventies. It was one heck of a store. As far as variety went, it specialized pretty much in either Green Tree Pythons or Emerald Tree Boas. You know, the ones that look alike – I am not a boa guy and hopefully got the names right. I do know that his breeding of these snakes back then was quite an achievement. He had tank after tank set up with baby snakes, and breeder adults. The owner also had some other herps, but it was mainly those boids. I bought some snakes there. I did not have lots of money back then (come to think of it not now either), so none of those high end snakes for me. I remember that I got my first Sonoran Gopher Snake there, and I think a Chain Kingsnake. I also was talked into buying, by the shop owner, a copy of The Keeper and The Kept. How I wish I still had that edition! It was the best non-animal herp related item I have ever purchased.
As far as variety of herp supplies goes, I usually do not buy herp supplies from a “reptile store”. I am guessing you mean a herp specialty store or a shop that specializes even more to just sell reptiles, and that you do not mean a general pet shop. Herp stores are usually way too expensive when it comes to supplies.
A large variety of animals is more likely to lure me there than is a large variety of supplies. I am a snake guy, but have kept and do keep other herps too. I like to see some of everything when I visit a shop.
A large variety of herp related books might also be nice

, but at a good price because I can usually get books on line or at shows at great prices. I may pay more at a herp store for a book or a herp if when all things are considered such as shipping charges, or gas and tools and entry fees to reach a show are factored in to my figuring.
A surprise, at least for me, is that you did not make the price of the herps one of your choices. Remember we are talking about factors that matter when making a purchase! If a herp shop has an animal for sale at a decent price and all other factors are ok, I would consider buying it. If on the other hand the prices are sky high, and I know all I need to do is to wait to get the same animal, of the same quality, somewhere else at a significantly lower price, then why even think about buying it at this shop?
As far as a convenient location goes, heck I have traveled as far as – well pretty darned far just to visit pet shops with herps and even further for herp specialty shops. I have driven at least 200 miles each way to attend a herp show, and probably have driven at least 75 miles each way to visit a herp specialty shop.
