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Do you mean not too competitive, RPG-style, perhaps with someone acting as Game Master?
Song of Blades and Heroes would be a good starting point for small sized forces. The basic combat and activation mechanisms are simple, but very effective. Then there are lots of special rules / traits you can add to customise your forces. As you build forces you could look at Dragon Rampant. This is several small units a side.
I second Song of Blades and Heroes! The "advanced" edition adds a good deal more spells and a reaction mechanic. There's an expansion for campaigns. It's a nice rules set that is simple at its core, but you can scale up the complexity with more models and expansion books.
Does this mean Ss&SS is no longer working for you or are you after something that is competitive? Would Blood Eagle not fit the bill? I believe it allows for small group activations. Vanguard and the skirmishy game from GW (the name eludes me) look interesting but I don't have the rules for these to really comment.
Fistful of Lead will be getting a Fantasy supplement down the road.
FFoL has cannon fodder groups, we’ve used them in our medieval, gothic and old west games. 3 figures that used d8 instead of the normal d10 and are killed with one wound. Works very well.
Warlord are releasing a set of generic fantasy rules in January.
Have you tried FUBAR? There are several fantasy and medieval variants, and they're all free. I came across them when building up 15mm units for Xenos Rampant, and what got my son and I into the game was the fact that you can play with units of any size. The rules are explicitly aimed at asymmetrical games, and they work very well.
Try Rangers of Shadow Deep. Just played my first ever solo game and really enjoyed it. I think it should hit the marks you need. Very much scenario driven, but it is heroes-players vs baddies-in-game AI. Totally fun!