I found the totalwar total realism mod to be quite satisfying.The screens I posted were from the Extended Greek Mod and that particular unit is expensive to train and takes 30 turns to recruit, so it's balanced for it's high stats, I think.
In the un-modified game, I think it's justified. Without high valor, armor, and weapon upgrades, they are good, but not too overpowering. The unit itself is a highly dumbed down abstraction of the spartan warrior system and works to simulate the way the unit works as a hole. I think, though, that giving them 2 hitpoints is a bit much, as no matter who you are, getting gored by a spear is going to put you down, but then, why give Generals multiple hitpoints? I don't think I'v ever had to face Spartans, though, so I'm not sure. I always save them for Siege towers, or as my reserve force when I play as the Greeks.
I like my Romans Pre-Marius, because once that trigger fires BAM my ultra-useful Hastati and Princeps (rarely build up to Triari in time) are un-replacable, and instead I get ultra-lame Auxilia, except in one or two higher-tier cities where I probably can get the Early-Legionnary Cohorts. Also, I mourn the loss of my Equites for Roman Cavalry and Auxilia Cavalry, and 2 turns to build Legionary Cavalry? No thanks.
Once I start rocking the Legionnary Cohorts, then I begin to thank Mr. Marius. I generally ignore the Praetorian and Urban Cohorts, as I ignore almost anything with a more-than-1-turn build time, with the exceptions always being Druids and Berzerkers.
Now, for Barbarian Invasion, I made the Celts into a playable faction, and I must say, they are extremely powerful. Once you take Southern Britannia, you're sitting on a giant money-machine, and from there, you just take your pick on any number of small-garrison Roman towns/cities, or you can just pick off the Saxons. Their Gallowglass unit is excellent, but heavily vulnerable to archers due to their defense being mostly skill, rather than armor and shield.
I like Alexander, but the game is messed up with 2 turns = 1 year. I'm advancing at what I think to be an aggressive pace, captured a couple of cities in West Perisa...but Alexander is already 27...he was only 33 when he died! There's no possible way I can finish at his pace, and I don't see how you're supposed to when it takes 2 turns to train a phalanx unit.