I don't know if this will help, as I have not heard those exact two models from Avalon and EgglestonWorks, however, I have heard and compared the Avalon Eidolon and the Andra II speakers.
Both are cut from the same cloth, IMHO. Both image and soundstage incredibly well, and better than most of the other speakers I have auditioned in this price range. (Both speakers disappear from the soundstage almost completely.) Both have excellent mid-range and treble response. Now, both do need a bit of power to get the most out of them, (I recommend at least 200 wpc minimum). Also both speakers, and especially the Eidolons, need to be brought out into the room, in order to achieve the best sound from them. (Both are fairly finicky about room placement, but this is fairly common with full range speakers, IMHO anyway.)
The differences between the two speakers are slight, but there nonetheless.
The Eidolon only has the sin of omission IMHO, (which most audiophiles prefer), as the deep bass response is a bit weak, (below 30 Hz). Other than that, it has a very flat frequency response from 30 Hz on up to 20K Hz. It is a very fine speaker. (The aesthetics are very nice, especially with the birds-eye maple veneer.) One of my favorite speakers.
The Andra II on the other hand has much better deep bass response, (down to 20 Hz with a bit of room reinforcement). But unlike the Eidolon, it does not have as flat a frequency response, as there is a slight mid-bass hump. (I prefer the treble response of the Andra II, as it uses the Dynaudio Isotar tweeter, but the Eidolon is not too far behind in that respect.) The aesthetics of the Andra II are very nice too, especially with the black granite side panels on the upper enclosure and the piano black veneer below. But in this category, I would give the nod to the Eidolons with the birds-eye maple veneer.
In case youre wondering, I purchased the Andra II speaker, as I really wanted to have a true full range speaker, one with that last bit of bass response. (I have done enough room treatments to minimize the mid-bass hump to where it is barely noticeable. In fact most people don't even notice it.) I have owned them for more than 2 years now, and I am still very happy with them, and have no plans on changing them out any time soon.
The Indra, the successor to the Eidolon, should sound nearly the same as the Eidolon, (although it looks like it might be just a bit more bass shy than the Eidolon, due to the use of dual 7 inch woofers versus the 11 inch woofer the Eidolon used). The Andra III, the (obvious) successor to the Andra II, is also slightly different, in as that as it has aluminum side panels, (instead of the black granite side panels), and it is now a ported speaker. (I did like the fact that the Andra II was a sealed design, as it did not interact as much with the room as my previous ported speakers, (the Revel Studios). However, I did pull the Andra II speakers out from the wall as much as I could, as this minimized the mid-bass hump even more.)
That is my two cents worth anyway.
And, Good Luck in your search!
Both are very fine speakers I am sure.