I just bought a Suzuki LZ400 Quadsport, same as the Kawasaki KFX 400. I looked at all the quads and wanted a good compromise between trail riding and jumping, etc. Reverse was a must.
I didn't need an all out race quad like the new 450 from Yamaha or the new 450 from Honda. These are about a $1,000 or more expensive and aren't needed if you aren't racing. I don't think the Honda has reverse either.
I looked at the Hondas such as the 300EX and 400EX but most people said they are outdated and not as fast without mods. Also, the 400EX doesn't have reverse and the 300EX is much slower and has poorer suspension.
The Banshees are fast, but are high maintenance from what I've heard. Banshee's are better suited for wide open spaces, from what I understand. The Raptors are good quads too, but are known for being top heavy in stock form, which in the end turned me away from them.
The Polaris Predator is nice, but Polaris is new to the sport quad scene so I stayed away from them based on some recomendations from friends. Not sure if it has reverse though, but I would consider it if there was a Polaris dealer closer to me.
The Bombardier is more of a dune quad and is very expensive and huge.
The Kawasaki V Force KFX 700 is fast and also automatic, but is very big. This quad is most similar to the Fourtrax of all the above and is one of the faster quads because of its huge engine. I thought it was too big for tight trails, but if that is not an issue this should be a consideration. Has a driveshaft, no chain, and easy to put in reverse from the handlegrip. Think of it as a fast Kawasaki Prairie with a sport suspension, which is basically what it is. The lighter body and tuned engine give it lots of speed. I wanted a lighter and more nimble quad more suited to racing, so thats why I went with the smaller 400 over this one.
The Suzuki LZ400 Quadsport/Kawasaki KFX 400 are known for their all-around handling (they are like a Honda 400EX, but faster and with reverse). They are not the fastest, but fast enough for me and have none of the issues of the other quads listed above. I could always put some mods on it to make faster down the road if need be.
I think I covered just about all the newer sport quads from the big 5 manufacturers. All of the other quads won't be much faster than your current quad. Hope this helps.