We are looking for a "warband" skirmish style game.. so unit vs unit. This is the list of rules I've compiled that fit our parameters.
SAGA
WAB
Clash of Spears
Lion rampant
Fistful of Lead: Big Battles
Anything I've missed?
I've been looking for something similar and hopefully have found a winning combo with a slightly modified WAB - at least for enticing fantasy players over. Do a google search for "WFB warbands", a pdf should be the top result - it's for the old Warhammer Fantasy warband rules they had for free on the GW website that were basically reducing unit minimums and a few other tweaks alongside some campaign ideas.
To apply it to WAB I'd say start off without using characters, just use a unit's champion as the force commander, and reduce unit minimums to 3 (maybe 5?) for infantry and 2 for cavalry. From there it depends on what size you go for. A 500 point army will have 2 or 3 10-15 man units and can squeeze in some cavalry if needed. If you opt to do an escalation league from this level it's easy to add on the 100 points between games then you could have a big blow-off at the end. It's got a strong Tale of Four Gamers vibe when mixed with the escalation league idea.