Reviews and Facts
There are some very good yo-yo brand names and I am going to review them, and some of their yo-yos and yo-yo related products here. 
Duncan
Of course I had to start with Duncan. That name is still synonomous with the word yo-yo. If Playmaxx is Nike, Duncan is Converse.  And the Imperial is a pair of Converse All Stars.  The Duncan company is probably the main reason for the continual sucsess of the yo-yo, although the latest advancements in yo-yo technology have also spurred sales. While Duncans aren't the best yo-yos in the world, Duncan's make fine beginner yo-yos, and every yo-yoer probably remembers his or her first yo-yo being a Duncan.  Duncan innovated the butterfly shape, and their line of affordable, plastic yo-yos has been popular since the 50's. One disadvantage to Duncans is that the yo-yos have a tendency to split apart as they grow old, and otherwise, most of them aren't take aparts. However, Duncans are cheap and can be found almost anywhere, even when yo-yos aren't the hot toy item.
Playmaxx
Playmaxx.  This company has produced some of the most innovative and advanced yo-yos on the common market.  While the Cold Fusion (the longest spinning yo-yo) is extremely expensive, some others such as the ProFire, the Turbo BumbleBee, and the ProYo II, are very affordable, and excellent performers.  The ProFire, a sliding brass transaxle yo-yo, though pretty noisy (you think it's bad when you buy one, then the break pads where down and this thing screams like a banshee), is one of the best loopers I have ever used, and the ProYoII is the longest sleeping fixed axle yoyo.  The Turbo Bumblebee, and the BumbleBee GT, without a doubt are some of the top transaxle yo-yos under $20.  Playmaxx has been one of the top innovaters of of yo-yo technology, including rim-weighted design & the new brake pad system, that I imagine they will last as long as the yo-yo itself.
BC What's Next
Some of the best wooden yo-yos on the market are probably from What's Next.  Their president, Brad Countryman, has made wooden yo-yos for some of the best companies like Duncan.  Now he's selling some of his own master designs. 
Team Losi
This company is better known for their work in RC cars.  They have taken their knowledge of quality manufacturing and applied it to yo-yos.  Their line of BB (Ball Bearing) transaxle yo-yos are some of the best under $20, excluding the new Silver Series, which were a bit more pricy when they hit the market and still may be just over $20 in some catalogs.
Henry
The makers of the Viper, one of the triumphs of German engineering.  They have now created 4 new yo-yos, and introduced the AXYS system.  AXYS are interchangeable axles that can be exchanged from yo-yo to yo-yo.  This is extremely cool because they have made transaxles that are all in one piece. I know this is hard to understand, so visit yoyoguy.com, and look under Henry for a better explanation of the AXYS system.
Spintastics
Not the first name you need to know, but one of the first.  They have a widening line of  yo-yos, all of which are good for different things.  The Technic, a wooden axel, is a good all around, freestyle yo-yo.  The Tornado is the BB version of the Technic.  The Tigershark, is a butterfly, rim weighted, BB yo-yo, that is one of the best sleepers on the market, but just not quite as good as a Team Losi or BumbleBee.  One of the coolest yo-yos Spintastics has made is the Torch.  It is the brightest light up yo-yo on the market, and comes in BB and wooden axle models.  There are also some glow-in-the-dark models of different names.
Yomega
SSSUUUUUCKKS!!!!
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