I own all of the things you have mentioned and like them all.
The Feather Burner is very versatile. for the initial investment and a few bucks in ribbons you can have many different feather shapes. you will have to pay attention to detail to set up the ribbons and get consistency out of it. especially if you change shapes regularly. And lets not forget the smell of burning feathers. not a pleasant smell to most wife's. Currently a popular retailer has it for $99.00. I believe you can find it cheaper or used.
The Little chopper, retails for $20 to $28. You can find it for as little as 10 bucks used. I have several of them and they have done very well, with many hundreds of feathers chopped on them. They are easy to use and consistent, even for a dork like myself. you must buy a different chopper for each shape. you use a hammer to smack the top of the chopper to make the cut and is loud (this only mens something to you when you are sneaking some arrow making in the middle of the night when the wife and kids are sleeping)
Vario Clipper $57.50 for the initial investment. then $16.50 to change inserts (feather shapes). This chopper is extremly well made (german craftsmanship). 20 different shapes to choose from, custom shapes are available. This is a fantastic chopper that is very easy to use and change shapes. I have only done a few dozen with mine but absolutely love it.
So, everything i just wrote sounds like an advertisement. they all work well, it kinda depends on how deep your wallet is and what you are comfortable with. I would say that if money is an issue and you will probably only use one or two shapes, i would buy the little chopper. if you are willing to part with a bit more money, buy the Vario, i am very happy with mine (Herb at Herbs Archery is awesome to deal with).
Good Luck, you wont go wrong with any of them. Jack