Specific units questions

[I of the Storm]

Hmm, as long as there are some trees for them to deploy in, they can hold out quite good and can be lifesavers for early HRE campaigns for example.

[seireikhaan]

I suppose I should mention that I'm quite used to playing the XL mod, where there's a lot more early infrastructure, not to mention that peasants were removed from the game.

So, end result is that UM not only are basically the bottom rung of the military, but are obsoleted extremely quickly.

[Fagar]

You are absolutely right UM are outdated extremely quickly in the XL mod, and realistically they are outdated quickly in vanilla.
But for what they are, a cheaply raised and maintained garrison force they can be reasonably handy.

[caravel]

A unit that is useful in desperation is still not a good unit. Peasants can save your skin if used correctly and at the right time. I would prefer a unit of Vanilla Spearmen to UM any day of the week. At least the latter can hold off cavalry for a little while. Militia Sergeants are much more worthwhile and I tend to skip UM and only train if absolutely necessary. UM are only dangerous if they're well upgraded and are under a good general, by that time you might as well train a better unit to replace the UM.

The only factions that find UM even remotely useful in early would be the HRE, Italians or French. The English have Fyrdmen (and Clansmen, Kerns and Gallowglasses!), The Danes - Vikings, the Spanish and Aragonese - Javelinmen, Jinetes, etc and the eastern factions have either Slav Javelins, Slav Warriors, Jobbagy, Vikings etc. The Turks and Byzantine don't need them - for obvious reasons, the Almohads certainly don't need them nor the Egyptians.

Of those factions that just might need UM, namely the French, HRE and Italians, I would still rather train Vanilla Spearmen. Also as the French have Hobilars to use as flankers early on that really leaves the UM somewhat redundant as the AP advantage is small considering that there won't be that many armoured units to deal with right at the start of the early era. This really leaves only the HRE and Italians with a possible need for UM at the beginning of the early era.

[Martok]

A unit that is useful in desperation is still not a good unit.

QFT

While Urban Militia can be useful under the right conditions, they become redundant and/or obsolete so quickly that it's hardly ever worth training them. I stopped using them in any real numbers after little more than a year of playing MTW, and not at all in the last couple years. With the possible aforementioned exception(s) of the HRE & Italians, pretty much every other faction has at least one or more units -- which are also available early on -- that perform better than UM do. What's more, these other units are usually a better value for your money as well.