It depends on what you are interested in they have very different mechanics
One thing to note, if you’re deadset on playing ground realistic, it might be a good idea to also get aircraft for CAS and air defense. If you’re playing ground arcade, you will have planes supplied to you in matches.
I play USA ground and my max BR is also 8.7 with the XM-800T, and the XM-246.
That is my “grinding tree BR”. if you count premiums it is 12.0
Im half decent at ground RB but I’m trash at all kinds of air battles except sim battles (because I try to avoid dog fights)
Honestly I more interested in ground
How did you guys grind so fast?
I’m horrible at air too. When I learn air battle it so difficult to me.
It way sound dumb, but WATCH YOUTUBE TUTORIALS. it helps
Also, Every time you get a kill it is good to move to a different part of the map, to help prevent that person from revenge killing you. the only exception is if you are winning the round or you have a really good spot to cap them from.