I'd think of a Cavalier 64, small squaretop that holds 64 bottles, some mode models will dispnse both cans and bottles .
+1 for Cavalier 64. They're simple, well built, and you can usually find one at a decent price with some effort. There are two main types of Cavalier 64 - "CSS", which is bottles only, and "USS" which will vend bottles and cans. The early mostly red CSS are probably the most collectible, though none of them are really collectible in the sense of a Vendo 81, or even a Vendo 39.
If you just want a machine to use, the USS-64 is the best bet. As I said it vends both cans and bottles, and from what I've heard will handle some modern plastic bottles as well. You can find the USS machines in a woodgrain style, same style used in later CSS-64, and even in a relatively modern 80's red and black style. You could even have one restored to resemble the early CSS models, but you probably wouldn't the money back at resale.
Both the CSS and USS come in multiple sizes. The 64 is the most collectible, the 96 is probably the next most common. You can find 64's for less than $500 in working condition. The USS are usually more expensive due to their desirable versatility.
One last thing to note, the USS machines can't hold as many cans as the 6 1/2 fl. oz. bottles that give the machine the marketed capacity. A USS-64 can only hold 56 of the 12 fl. oz. cans, for example. The USS-96 can only hold 84 such cans.
You might also consider a Cavalier C-55, they can be found in working condition around $1000, and can even be converted to vend cans. Dimension wise, they're alot like a square-top Vendo 44.
Square tops are not currently very collectible as a general rule, but they tend to be considerably cheaper than the round tops. A good quality, reasonably priced square top is in my opinion a great way to get started collecting. Especially if you are on a budget, or trying to figure out how much money you are willing to spend collecting.
