They are all basically the same so you need to know what sort of features you really want.

Do you just need a keyboard or would you like to have other controls on it like faders, knobs, pads, transport controls, etc.

Do you need it to store MIDI presets or just be a set it and forget it type of controller?

Do you need it to be able to trasmit multiple MIDI channels at one time?

Do you want it to have a USB interface?

If you are unsure about those things, think about them. Think about how you will be using the MIDI controller.

I have found that the M-audio, Edirol, EMu are all pretty much the same, the differences being in the features they offer and size. Another big difference is in size. Do you want 25, 49 or 61 keys?

Personally, I love the CME controllers. But they are a bit more than what you want to pay.

The M-audio oxygen controllers are nice and come in 25, 49 and 61 key versions. Plus they include faders and knobs for controlling other things. They also include a snapshot feature where you can save settings to a compture and recall them when needed.

I personally use only a Yamaha P90 but use it only for note input for notation software and piano/sampler stuff. No controllers needed for my purposes. It is also a very good stage piano.

A friend got one of the small M-Audio O2s to use as USB input and it works very well for her.

If you are buying a controller for the first time you may have to hone in on your personal needs and preferences at some later point, as most of us do in all things.

I have a Edirol PCR-M50 which I find to be really good for what I need.

I produce electronic music and use alot of automation and effects in which the 8 faders and knobs come in very usefull and are pretty precise.

Seems to be a strong build and always seems to do the job

hope this helps