To answer your question, as others have said 6cm is it if you have to use factory ammo. Factory ammo in 6cm can be very accurate.
I'd like to point something out though. What takes so much space is the brass prepp stuff. You can have a scale and single press and load very good ammo and keep it to a 4'x2' section of bench or countertop even. A V3 set up, a FA hand primer, calipers, and a simple press is all you need. With
@Dave__th3__ss doing such a precise job of processing brass, and sizing it exactly to your specifications, you really don't have to do the whole thing but can still tune a load to your rifle and load your own. I'd think about that hard if I were you. It's still cheaper than factory ammo too.
For the money involved in prepping brass and annealing it ect.... you can pay for a whole lot of brass prepping to be done. It's also a massive time saver and super nice to just have several hundred cases ready to go whenever you choose. I process my own some but I send him a lot also and it's worked out just awesome for me.
I load for several calibers but I still choose 6cm because it's very accurate and fast while keeping me able to buy a bunch of factory ammo if I want to. (If we can ever do like we used to and buy 500 rounds of Berger ammo then load the lapua brass after shooting it for a reasonable price again, if things get sorted out after Joe's mess).