AoW2:
AoW, and to a lesser degree AoW2 too, have this charm/soul/whatever factor that makes you want to come back to them, imho. Both are heavily leaning towards combat and the simple economy part is about making more units to have said combat.
In both you can make uber heroes but at least in AoW 2 you can just limit the max level to mitigate it. Very pretty maps too (as long as the map maker doesn't ruin that with big, empty, homogenous spaces in the name of balance in case of custom maps).
The best AoW2 mod is the Glorantha one, especially if you get bored with the vanilla game or dislike single-unit units:
http://aow2.heavengames.com/downloads/showfile.php?fileid=781
... with this walls HP patch to make walls and gates sturdier to counter stat changes in units:
http://aow2.heavengames.com/downloads/showfile.php?fileid=841
It replaces all units, changes most of them into army stacks, makes low-tier ones useful, races more unique, shifts balance in regards to some immunities, flying units, some ranged units now lack melee attack, etc. The only ugly part are some of the leader portraits because the author took them from all corners of the internet.
There's also a map pack for it with the converted vanilla maps because it's not compatible with normal AoW2 ones (most intended-for-AoW2 maps you can still just open in the editor and resave, even a few heavily-scripted scenario ones - the not working ones will freeze the map generation/loading after the scenario setup part - but it's easier to just grab the ready archive).
You also can easily add music from AoW1 and KoDP to AoW2.
---
AOW3:
AoW3 lacks soul, has mods adding lots of construction options in cities, more map resources/buildings that add bonuses to the city they're in (Civ-like city ranges) and some units to make it more interesting/varied if you're into that, and disgustingly homogenous indep stacks. There's some (un-)balance mod that messes with many units' stats that makes it more enjoyable imho, though the last time I checked it the author tried to make frostlings lose HP outside of snow terrain and it made that race unplayable (something about them always losing HP each turn and then possibly regenerating the lost part, but it was a death sentence to wounded units and especially the AI had no idea how to keep these units alive).
Leader classes/traits/spell schools limit the customisation options during the game a lot (there are some mods that add merges of existing ones as new traits - you can use these to give yourself thematic-but-weak options and boost the AI by giving it a boss-tier leader), and do weird shit like passively giving most units you control magical attacks (and with a few levels and artifacts you end up giving all your heroes rainbow attacks with a dozen of ranged weapons with cooldowns).
Much less bottlenecking underground in comparison to the previous games because of wider corridors being generated in mapgen and more units having tunneling or rock-passing abilities.
Undead = mostly just a tag on normal units, with related boosts and vulnerabilities (can be a pro or a con depending on if you were expecting a completely separate race of zombies and skeletons), though the economic layer is different if you play as a necromancer (IIRC you need to raise city population with spells, deaths and migration).
Fliers use flying only to move vs being always in air an mostly unreachable to melee units in Aow1/2
The combat itself (sieges included) is still fun if you're not fighting against the copy/paste indie stack #674. AoW1/2 offer more visual clarity though. You should use the option to speed up combat animations (it makes the rainbow damage display unreadble but otherwise you have to suffer through the sluggish eye candy).
You may prefer it if you want to play as a pirate or a conquistador, or can't stand AoW2 looking blurryish nowadays.
In regards to RPG-ish experience, there are quests (including achievement-y empire quest goals that can give you things like a special building option if you reach them first - highest level AI seems good at rushing these btw), vassal towns (the latter is good if you don't want to bother with developing that frontline town that's already guarded by a strong creature), indep monster spawners (unfortunately these indeps are boring as hell and just there to distract or harass players), more unit rank tiers (the level equivalent for non-hero units) and some mods expanding on these and on hero levelups (not sure if fun).
AoW2 has optional shrine quests every now and then (with half of them being cripple-yourself-by-razing-your-structures ones). Both have monster lairs you can explore to gain artifacts, units or resources.
---
Time-wise both can take time to process turns later on when there are more army stacks running around, especially on larger maps, and big battles and sieges will take time to finish. If you don't mind the risk of auto-resolve, you can use it to skip uninteresting/easy-victory battles. The initial phase of spending turns developing towns before they're useful seems to be longer in AoW3 (but maybe my setting preferences are to blame? there are more quick game options there that I've never bothered with).
TL;DR - AoW2 if you want something closer to AoW1 and/or more combat-oriented experience, AoW3 if you want some Civ in your AoW.
AFAIK, neither are quite like MoM (haven't played it yet, unfortunately), so you shouldn't set your expectations too high, though both are good games on their own (even if I can't force myself to play too much of AoW3 in a row).
if Triumph was still independent.
