For starting out the SW ED80 is great... gives a nice wide field of view that you can fit alot of sky into.. It does however limit your ability to image some objects as they will be fairly small in the field of view.
The longer focal length of the 100mm will be better for some objects, and not as good for others.... it depends on what really takes your imaging fancies. The 100mm will require more accurate guiding to ensure pinpoint stars
FWIW the aperture difference between 80 ~ 100mm makes virtually no difference to photography.
The equinox refractors are a step up over the ED series, using different glass elements, a better focuser among other things... Note that the Equinox 80mm is the same as an Orion EON 80mm, and both are clones of the William Optics ZS80. The Orion is somewhat cheaper than the Equinox from memory, $959 vs $1180 or so for the Equinox. Considering they are the same scope with a different brand name, I know where my money would go
What mount do you intend to put one of these on?