2 10 man DA in serpents with either shuricannons top and bottom or scatter and cannon bottom.
keep 5 DA man as foot sloggers to grab objectives. no exarch needed for DA most of the time
one massive guardian squad with a warlock and 2 platforms (if you have em.... and magnetise the guns too)
wraithguard in serpent with seer (scythes FTW)
use vypers to pester flanks (keep em fast and in cover) same with jetbikes but also objective grabbers
i would get some fire dragons and reapers, pop the dragons in a serpent if you get another
or switch for one of the avengers WS and foot slog the DA
reapers don't really need the exarch TBH and are lethal.
the thing i find with eldar, buy what you like the look/feel of. you have a load of stuff......... play some gaps and fill in the gaps where you feel the synergy is lacking