Fighter planes have the advantage of being able to get to almost anywhere AI air power may appear and can most easily take the battle to the AI, but suffer several disadvantage's, being shot back at, not being able to get too close when AI AA units are near and at least for me almost always being back refuelling when the next wave of Russian air spawns. Planes also have the capacity when safe for them to do so, to reduce entrenchment and chip away strength from AI ground units in a way most AA units cant.
AA units refuel/rearm in place when free to do so and can get right up near enemy AA providing some air cover to units planes couldn't, they are in general cheaper than fighters given soft cap rules, but almost without exception they are one trick pony's. All they can do is shoot at AI air units when they are around, otherwise they are useless.
That said, I'm considering moving from two to three AA units now I'm heading into 1943, I currently have two 88mm towed AA units (2 and 4 stars respectively), so what do I do? I have stuck with the switchable 88's until now because they have been my most effective AT unit more than their pure AA capabilities, but with Tigers here and Panther/Elephant's around the corner, do I really want to be risking OS AA units in an AT role. If I'm not going to be using the AT capability wouldn't I be better off swapping them to SPAA, so they can keep up and not be in transport mode just when they need to be providing AA cover?
The final issue is if I'm adding one more AA unit at the start of 43, what is the best way to do it. I could convert my two existing 88's to SPAA and buy a new green 88 for upgrade maybe start 44, the new 88 would operate where possible in AT mode still to get it up to 2-3 stars fast while the upgraded SPAA would provide close air cover?
Of Course it may be that post 43 as deployment limits shrink there will be less room for AA units, no idea until I get there.
What would you do, restarting 39 and growing three rather than two 88s not being an option

Cheers
Bone