GRB is combined arms, focusing more on Ground but facilitates both air and ground combat.
I prefer that over what would be just WOT with better damage models.
I understand that CAS can be frustrating, and so I believe having the option to queue in for CAS-free lobbies would be an interesting addition - and definitely helps if you don’t have an aircraft of your own or SPAA to farm them with.
Depends on the BR I’d say.
Most Low Tier BRs (1.0-6.7) have fairly decent SPAA (Skink, Wirbelwind, ZSD63/PG87) and some broken SPAA (Coelian, Ostwind II), as well as fairly decent CAS aircraft (P-47D, Yak-9UT, T18B, Do 335, Pe-8 / Lancaster) and some broken CAS (Yak-9K, Tu-2S).
Most Mid Tier BRs (7.0-10.0) have much more potent SPAA compared to CAS (Gepard / Gepard 1A2, ZSU-23-4M2, PGZ09, ZSU-37-2), especially the M247 and Imp Chaparral.
They also have very potent CAS, but can struggle to kill AA / Air if not really careful (Scimitar, Sea Vixen, SAAB-105G, Ayit, Alpha Jet, F-84G-21, SK-60B, A-4B).
Top tier (10.3-12.7) has some of the biggest difference in capabilities between AA and Aircraft.
You have some really good SPAA (Like Strela, Type 81, Pantsir, 2S6,), but the CAS is much more difficult to kill, especially in an uptier.
The Pantsir (12.0) can see the AMX A-1A (11.0), which the AMX has no chance of killing.
On the other hand, the Pantsir can see the Eurofighter and Rafale (12.7s), which the Pantsir has near to no possiblity of defeating.
Those Top Tier aircraft can also fight other air, which makes them invulnerable if played correctly.
Top Tier needs the most decompression (in my opinion), especially by decompressing the AIR BRs for GRB, as well as the 7.0-9.7 range for ground vehicles (but you can only correctly decompress that area if every BR above it decompresses too.