In order of preference
century XVIII
Post Honors
Der Alte Fritz journal rules
Honors war

FIW
Rebels and Patriots
Muskets and tomahaws

Napoleonic
Home rules (compendium of many rules)

Thirty Years War
PiKemans Lament (small battles)

I also like them although I almost never play
Hail Cesar
Rampant lion

Like the previous respondents the group I belong to use a variety of rules, mainly because we have people with different interests so we play different rules for different games.

Ancients - Initially we started playing WRG 6th Edition though this was superseeded for most of us by Warhammer Ancients, until a few years ago we started playing Lion Rampant.

Late Medieval/Renaissance/30YW/ECW - WRG - though it looks like Pikeman's Lament may be picked up soon for the War of the Spanish Succession. We've looked at few others but the Rampant system works well.

Napoleonic - WRG 1685-1850 - and that may get a bit of a reboot for the 7YW.

Fantasy - Dragon Rampant

As well as these we play Cruel Seas, Tanks, and a few others.

Ancients - To the strongest or an adaption of Command and Colours.

Dark Age - Songs of Blades and Heroes, adapted Command and Colours, Tribal.

Medieval - Lion Rampant.

Colonial - Men who would be Kings.

SCW - Bayonets and Ideology.

WWII - Crossfire, Bolt Action.

Modern - Black Ops.

Really like the Osprey range and also the Ganesha Games sets, particularly, Fear and Faith for when things go bump in the night.

The "Perfect Captain's" free range of rule sets are amazing in their innovation:

http://perfectcaptain.50megs.com/captain.html

"Red Actions" for the Russian Civil War and related nationalist conflicts in the period
"Cousin Jonathan" (battle) and "John Bull" (skirmish) for the War of 1812
"Spanish Fury" + "Very Civile Actions" for the English Civil War
"A Coat of Steel" War of the Roses modification for contingent/retinue based 12th-14th century samurai gaming

http://perfectcaptain.50megs.com/acos.html

"Chain of Command" seems to yield good games for the Spanish Civil War on the TMP board

http://theminiaturespage.com/boards/msg.mv?id=452301
http://theminiaturespage.com/boards/topics.mv?id=321

For the record I absolutely ABHOR pure I-GO-YOU-GO systems with endless silly fantasy modifiers to remember and where one side stands around like frozen idiots being massacred cough-SAGA-cough (pg 33-35)

Oh I don't know.

Getting an advantage for being able to get the first blow/shot in seems a reasonable justification for some i/go-/u go. And a round of combat surely represents only seconds of real time. Hardly standing around "frozen".
We'll have to agree to disagree here. One man's meat, Steve, is another's poison?

I'm not entirely sure why you eschew modifiers. Simplicity?

I am well aware of the current trend for simpler rules & I am glad these meet a lot of people's expectations. I do remember the complexity of rule sets such as 'Empire' but I'd be reluctant to criticise those who have & still do play them.

My tastes lie some where between the one page Simple rules & the many page encyclopedias.
My justification lies in the idea of tactical challenge. Modifiers provide a smorgsboard of options for you, the table top general, to chose from. Here lies the challenge and, hence, the fun. My opinion only, of course.

Your disdain for SAGA is your business, of course. I know we use it not for some supposed 'realistic' depiction of Dark Ages warfare but for a bit of fun. Our little group of 5 or so laugh & smile more whilst playing SAGA than any other wargame. Is this enough reason for playing SAGA?