In my Imperial Fleet I run 6 Cobra destroyers (2*3) and a squadron with 2 Sword and 1 Firestorms (if the 2nd hand deal had 3 Swords it would've been 3 Swords).
I like the small torpedo markers. I think this is mainly caused due the fact I had my Tau fleet before my Imperial Navy.
In my 1500pts Tau fleet I run two Castellan squadrons of 3 and one Warden squadron of 3. Love both, Wardens are great when the lines close.
In my admech fleet I have 3 Gladii and 3 Hunters (heh).
In my main chaos renegade fleet 6 Infidels and 3 Iconoclasts (aka Emperor BB killers).
(see a pattern with torpedo escorts?)
Corsair is a lot of escorts, I have not used my Aurora or Solaris yet but otherwise I run one or two capital ships (Void Stalker and/or Void Dragon (Flame)) in my Corsair fleet. Rest escorts. Nightshades are the ones I prefer most but Hemlocks and Aconites are awesome as well.
Craftworld is the only fleet I sometimes field without escorts, this due background story (eg Shadowhunters are last line of defence of Craftworld and/or scout ahead. Never part of battlefleets).
My Rogue Trader list is always in the build, variety of things is what I aim at.
My Dark Eldar list (unpainted) is per fleet list: 9 escorts, 3 cruisers.
My inbuild Vanguard list for Nids is escort only, lolz
My Marine list is smaaaaalll (1 vbb, 1 strike cruiser, 2 escorts)... needs more.