There are some differnent types of juggling balls(actually very many) and on this page I will write about some of them. If you're a beginner I say you go for the beanbags. When you have learned a bit more you will still find the beanbags great for learning new stuff, but on the other hand stage balls look and feel better. And you can do contact juggling with them (for example butterfly). The problem with stage balls is that they always end up under your bed or in some other inconvenient place. Then you buy a DX-ball with all the characteristics of the beanbag and all the characteristics of the stage ball. Then there is the oddballs, the bouncing ball with 80 % rebounce (the best toystore balls have around 60 % rebounce). As I mentioned above there is a thing called contact juggling. When doing this, acrylic balls and silicone balls are the best. Silicon balls are also the ultimate ball for bounce juggling. A little bit less rebounce than the oddball , but incredible spin and feel. The price however is astronomical. Some balls are available in different sizes.
This is the best ball when it comes to learning. Filled with bird-seed, and with a fabric that can deal with the roughest floor (even outdoors). They don't roll when you drop them. All they do when you drop them is give away a slight ploff sound. Thanks to its squeezines it is very easy to catch it even if you don't get a good grip. Beanbags cost $6 each or more. You can find beanbags packed in a set of three for the same price, but they are filled with plastics and the feel is not even remotely near the real beanbags. The result is that it becomes harder to juggle. If you think $6 each is too expensive it is possible to make your own beanbags. Filling a sock with unpopped popcorn is one way. Filling a ballon with peas is another way. The beanbag should weigh around 120 g. They come in an infinite (almost) number of colors.
This is a ROUND, hollow vinyl ball. It weighs a bit less than a beanbag and it comes in a large variety of sizes ranging from 68 mm to 102 mm. The perfect roundness makes it good for contact juggling, but it weighs a bit too little (a silicone ball or acrylic ball is the ideal ball when it comes to contact juggling.) The stage ball has almost no bounce, but is very good at rolling under the bed. They are available in many different colors.
This is my favourite among the balls. It's a mix of a beanbag and a stageball, which means that it's perfectly round but also squeezable. It's possible to do contact juggling with, but the silicone ball and the acrylic ball works better. It's almost bounceless, and it doesn't roll as easy as a stage ball. It's fully waterproof. It's great to juggle when it rains, and if you buy the hevier DX pow3r balls you can even juggle under water ( it works, I've tried it:). The DX-ball comes in a large variety of colors with some flourescent and illuminative. They come in three sizes (62, 68 and 75 mm).
If you want a ball with exceptionally great bounce I say you go for the oddball. As i wrote at the top they have 80 % rebounce. This means that the ball will bounce at least 30(!) times if you drop it from shoulder height. These balls are okay for contact juggling, but it's horrible when you drop'em. A true juggler have at least two lost bounce balls under the furniture. If you can't afford silicone balls I strongly recommend oddballs. It is possible to bounce-juggle with toystore balls, but they are often too small, and the bounce is too bad. The oddballs are only available in one size, but they have an infinite (at least I haven't seen two like balls) variety of colors/patterns.
This is the most expensive juggling ball. The bounce is slightly less than that of the oddball (75 %), but the silicone balls spin a lot more. It's great for contact juggling, but you've got the same problem as with the oddball. If you drop it your ming vase (or the ugly pot you made in school) is history. A silicone ball doesn't get permanently dirty. Just pour hot water on it and the stains go away. A silicone ball weighs between 120 and 270 g (270 g is more than most clubs weigh). It feels better to juggle with heavy balls. Silicone balls come in 4-5 sizes and 7-8 colors depending on the manufacturer.
Acrylic balls are transparent (sometimes not) balls of plastic. A juggler performing with acrylic balls always seem a bit mysterious. If you've seen Labyrinth with David Bowie you know that acrylic balls are the best ones for contact juggling. They have virtually no friction against eachother, yet you get a good grip. Acrylic balls look great in tricks with lots of movement. For example weave, fake and robot.
The beanbag is usually (almost always) 68 mm in diameter. The stage balls are often 75 mm, but performers often use a bit larger ones because it lookes better. The problem with large balls is that they are harder to juggle with.