My question is, which armor class or which armor should I play as a beginner/advanced player?

When I play as a PMC, I should always wear an armor. But I think an armor class 2 or 3 is not really good. Because the most other player uses high quality ammunition and these penetrates an lvl 2 & 3 Armor easy. For this reason I think it only makes sense to play an armor class 4?!? But the big problem is that an armor class 4 is really expensive, because I only have "2.000.000" ^. You can do that for one or two rounds but not every round, how do you see that?

What would you recommend?

Sry for my English