Two totally different animals the ADS and Focals. For the best solution he really needs to try and demo them.
If that's not an option, I'll try a little bit to explain each. The ADS with be much more "relaxed", with a tad bit more midbass capability (depending on install of course). The Focals scream. They are bright, detailed, and will blow you away with their sound. The downside, is after an hour or so, your ears are bleeding. The Focals are not as good for extended listening periods.
I owned the Polyglass set a while back and I really liked it. I've since moved on though. If your friend is new to car audio, and this is the first higher end install he's done, the Focals may be the answer.
If your friend kind of knows what he's listening to, and has opinions on what he likes, then the ADS is a better option.
Some others to look at are the Pioneer PRS720 set, or the Alpine SPX-177. There's a huge collective boner for the Pioneer set going on right now. It's for good reason. It's a very nice set, and doesn't break the bank. The Alpine set has one of the best crossovers out there. It's extremely flexible, and let's you dial in sound a lot better than any other set in that price range.