Are Apex engines good for vacuum?

I'm having a hard time with Mage engines, particularly on Second Stages or with heavy payloads (For the latter I use Apex which is not a problem). I am having to use Apex on 2nd stages with what seems medium payloads due to the Mage engines feeling a bit underpowered, so I basically end up using Apex for all stages and maybe pixie on any landers if needed.

I am ok with Apex engines on 2nd or latter stages, I am just wondering if I should be using Mage engines with increased fuel consumption and reduced weight, in case Mage engines are optimized for vacuum, or does it even matter which engine I use at this point of game development? or can anyone suggest any engine types, settings and weights I should be using on the different stages (2nd and later)?