I've done research on all of these, though I have only seen the AA louvers in person. Here is what I know about each:
Ebay lambo louvers:
Look pretty nice, but come in a rough textured plastic which would make it a pain to paint, if you want to go that route. Don't know much more about them. If these were offered in smooth plastic instead of rough, I may have gone with them.
Ikon louvers:
Apparently has rattling problems, and the bottom most louver touches the back edge of the trunk lid when it opens, which can cause paint damage on the louvers and/or trunk. I don't like that the bottom of the louver is filled "solid" in the middle.
AA louvers:
Has the fewest louver blades of those that are offered (5 vs 6). They do not come out of the molds very cleanly, leaving lots of rough edges, chips in the plastic and wavy edges. One member here had the bottom mounting surface of the louver warp after leaving it in direct sunlight for a while - AA provided another mounting point to the customer for the middle and that apparently fixed the issue. These are the ones I went with because I like the fewer blades and overall look - I am hoping to take them to a body/paint shop to get the edges cleaned up before paint. Here is an old thread with lots of pictures of the AA louvers, including closeups of the rough edges and warping (check page 4):
https://www.camaro6.com/forums/showt...hlight=louvers
Despite all of the problems, the AA louvers seem to be the most popular. They were also the lowest priced of the three for awhile and commonly go on sale from AA's website, so that probably contributes
One other thing I have learned is don't use the supplied adhesive for any of these - replace them with gorilla tape.