Alright, then...
Actually, the Abrams has depleted-uranium armor layer in chobham configuration, it's not considered a ceramic armor.
The Leopard 2 uses ceramic armor, though, which is more expensive. Rumor has it that the Leopard armor uses other heavy metal in its matrix. The armor is supposed to be in a 2nd generation now.
The Russians and Israelis use 3rd generation reactive armor. The israelis have 4th gen armor and are about or have already issued 5th gen armor.
The british use 2nd generation chobham armor.
Yes, physically the Abrams has the most armor mass of all. This may have changed somewhat now with newer Leopard 2A6+ and Merkava IV+, but still in a top position.
T-90 can be repaired in the field after hitting a mine.
M1A2 -
M1A2SEP increased mine protection, additional reactive armor for sides
Leo2A6+ increased mine protection, increased modular front and top protection; PSO: additional reactive armor
Merkava IV increased mine protection, modular armor field exchangeable, full electric
------------ M1A2 M1A2SEP Leo2A4 Leo2A5/6 Challeng.2 Merkava4 T-90S
kinetic RHA. 800 940-960 590-690 920-940 920-960 790-820 420-920
chemica. RHA 1300 1320-1620 810-1290 1730-1960 1450-1700 1530-1650 580-1340
The T90 electro-optical jammer is certainly a nice/cheap solution, but I have doubts about guided air-ground weapons.
Reason being detection of line-of-sight, which works well for ground attack, but air and on the top?
Doesn't work against JDAM or IR scanner killer munitions.
Merkava IV,
K-2,
T-X have electro-optiocal and IR jammer, and more
Vulnerable armor spots:
Abrams
turret sides, back
engine aft, weak enough for normal machine gun to penetrate
(hull sides ignored)
can't say about electronics since that's Tempest secret
Leo2
similar to Abrams
aft better armored since exhaust is on top
Merkava IV
right side engine-exhaust
125mm verses 120mm cannon: 7% more kinetic energy penetration under same conditions and munition type
Western barrels have a five time higher lifespan. German cannon will be improved...
Russians fire missiles; have higher effective range than western rounds; autoloader might jam
Merkava fires APAM-T, and LAHAT missile; most ranged engagments of 'western' tanks; best targeting system
Leclerc supposely best artillery computer
Targeting:
M1A2SEP 2nd generation thermal vision
Leo2A6 3rd generation thermal vision
Merkava IV, Korean K-2, Japanese T-X integrated battlefield system
Mobility:
Leo2 best overall as it can dive into a river; engine change 7-15 min.
Merkava IV most comfortable and greatest speed on any terrain; field repairable; engine change > 1hour
K-2, T-X most modern designs
M1 worst mobility endurance in terms of fuel and damage; in iraq most were damaged by just driving around.
T90 supposely drive 700km before repair is needed. If M1 drives 35 km around the city a day (between check points). It would need 20 days until repair, but somehow this does not explain over 200 needing repairs in the first 3 years.
Well, M1 vs Merkava exercise results are also kept secret.
All in all, it depends on range and the first shot. At longer range the T90 has an advantage with it's missiles.
At close range the T90 will lose because of bad targeting and physically thinner armor.
Home
But it was worth it - simple and reliable as crowbar. But it's 4.0L and ate 16-17 L/100 (on my grand cherokee) while having 190 H.P.
Btw, maybe you wanna try to make something in more "popular" style this time? 1-2 well developed main heroes and reader get most of the picture from their perspective. You know - less Herbert and more Garry Garrison, more adventure, less politics and static details.
I hope you'll explore all but "big millitary" aspects of Seikai universe more - things official story is not very rich with.
It's just that when officials at such level show such unhidden disrespect - its a grim sign. 
