880prs has more options if your lookng to go active such as crossovers and such.
if you're not running active, it just depends what one you think looks better i think. i had the 7800 for a few months and it was a nice radio, but i LOVE my 880prs..
880 has alot of nice functions and is a great unit for SQ
the other 2 hu you listed have the bling factor to them, but im pretty sure the 880 has more options to tweak your music to make it sound the way you want it