I've not used either for imaging yet. However for pure visual use the Megrez was worth every bit of the extra cash ($300 more cash) looking at high contrast targets like Jupiter or the moon, the EON shows the faintest of faint purple tinge towards edge of the limb of the moon, Jupiter through each scope is much of a muchness.. the Megrez is easier to bring to focus at higher powers (could be more due to aperture than the focuser) although the overall feel of the megrez is much nicer...
Should have images through it early/mid next week... (depending on how much the moon hampers my attempts..
If spending an extra $300 is not an issue, the Megrez 90 is what I would buy. The orion is a great little scope, and for imaging im sure it will preform brilliantly, but when attempting to be objective, something has to come second
From what I've seen, the skywatcher does not measure up to these two. although depending on where you buy, it could be as low as half the price of the megrez 90, and many on the forums have proven its a very very capable scope...