-- Concerning Defaults -- I would replace Trisquel's current GNOME fallback-based desktop with MATE. Trisquel tries to present an accessible, traditional, and user-friendly desktop experience, and I still think that GNOME 2 itself is the way to do it, rather than having to fight GNOME 3 into shape. GNOME fallback (at least in my experience) has always performed a *lot* slower than MATE, which performs almost as snappily and lightly as Xfce. Not only is MATE reasonably lightweight and responsive (like Xfce) it is very integrated and newbie-friendly (unlike Xfce, which has clear influences from its 'geek' heritage). It is truly the perfect combination of speed and functionality- ideal for a distribution such as Trisquel.
If GNOME was replaced with MATE as Trisquel's official DE, I would get rid of Trisquel Mini- MATE is light enough for older hardware anyway, and the continuous maintenance of a separate distribution is just duplication of effort- Trisquel Mini is buggy all over as it is. All effort should be concentrated on the new Trisquel 8 MATE. I would continue to provide only two separate variants of installation ISO- a minimal network installation ISO, and an 'official' variant for newbies with MATE preloaded. -- Concerning the installer -- This is more for me than anyone else (since everyone else seems to be gushing with praise for it)- but I absolutely hate the graphical installer. Not because it's graphical, necessarily (the Debian graphical installer I think is excellent) but more because I don't like the way it doesn't offer much choice and has its options strewn all over the place. I think it is far better (and I daresay more user-friendly) to have an installation procedure that is step-by-step and asks one question at a time. For the Trisquel installer, I would use the Debian text-mode installer as currently offered on the netinstall CD. If graphical prettiness is *absolutely* necessary, then I *suppose* the Debian graphical installer could be offered too, which IMHO has a far nicer layout than the current Trisquel graphical installer. Just replace the Debian banner with a Trisquel one, and job done. -- Concerning the actual OP -- I use Xfce, since my computer is quite slow. I also just generally prefer Xfce, followed closely by MATE.