Sharmie wrote:
I mean when I mean low level units I mean by moderately only mostly I reach lvl3 infantry and stop there, since my units are crazy cheap and have fast production times at that moment. Itβs mostly great against axis units since they canβt combat cheaper,stronger and moderately nice and well rounded enemies.I normally use cheap units and when I mean cheap j mean just enough Comintern is like cooking steak, you do it too much it gets burnt, you cook it too little: itβs still raw.
So when playing Comintern you just have to get the right amount of what you need already I normally suggest lvl 2 armored cars/light tanks and lvl3 infantry and for sp arty I tend to use lvl1 since they are cheap and you just need a lvl2 secret lab to get things going well only (mass production) by the end youβll have 100+ units pitted against the puny 50 or less german nations army.
note: this is just my reccomendation Iβm still pretty much a Novice at this (not very well) so please if you see anything wrong Iβm free to any criticism! 
I have some thoughts, opinions, and facts to discuss if you don't mind constructive criticism. Being open to criticism is how you improve so you're already leaps and bounds ahead of the average armchair general who insists he's always right
On the topic of higher levels vs lower levels, let's do a comparison of level 3 infantry and level 6 infantry from the Comintern research tree. Level 3 infantry will have 25 HP and its defensive damage vs unarmoured targets is 7.5, but let's say we have two of these infantry. Together they will have:
-50 HP
-15 defensive damaged to unarmoured units
-42 speed
And will cost:
-1,880 food, 56 daily upkeep
-880 goods, 26 daily upkeep
-1,860 manpower, 56 daily upkeep
-$1,320, $40 daily upkeep
-5 hours and 30 minutes of production time.
Now let's compare that to a single level 6 infantry unit, also from the Comintern research tree:
-50 HP
-16.2 defensive damage to unarmoured units
-51 speed
And will cost:
-1,500 food, 54 daily upkeep
-720 goods, 22 daily upkeep
-1,300 manpower, 39 daily upkeep
-$1,100, $32 daily upkeep
-4 hours and 30 minutes of production time
What this shows is that a single level 6 infantry unit makes a stronger stack than two level 3 infantry do, while the level 6 infantry is cheaper and takes less time to build. It should also be noted that the level 6 infantry is significantly cheaper in manpower.
You may think that the differences are not that bad, but since when do we ever build just one or two infantry units? What if we compared sixty level 3 infantry units to thirty level 6 units? Multiply both these figures by 10 or 20 or 30 and have a look for yourself what happens to the numbers.
The other major issue with staying at low levels is it limits the effectiveness of every stack you possess. Even if you can build 20 low level anti-air units, you can't put 20 in an artillery stack; you can only effectively use 10 of any single unit type in a stack. If a strong air wing comes up against your stack, you don't stand much of a chance. The same can be said about your weaker infantry going up against 10 Axis motorized infantry, or your artillery going up against 10 Axis artillery. By making more stacks you are essentially relying on one stack being destroyed so that the enemy is weak enough that your second stack *might* be able to defeat it.
Other smaller issues with making a larger army with lower research include slower speeds causing the enemy to outrun you and the fact that since you are researching higher levels less, you will have research slots open more often and are significantly more likely to research new unit types that are not necessary. It is considerably better to have high level armoured cars and tank destroyers instead of low level medium tanks, tank destroyers, armoured cars, and mechanized infantry. The high level armoured cars and tank destroyers will win every engagement, hands down.
I hope this wasn't too much of a read and I hope you find it useful! If you have any questions please feel free to ask away 