Hello and welcome,
for the time being I would keep using the high cap, the infamous "battle rattle" is a myth and only occurs when the magazine is nearly empty and you shake the gun.
G&G midcaps work relatively well (they're decent but the extended dog dick followers need to be yeeted into oblivion ASAP), failing that, Battleaxe EPM clones seem like the best bang for buck option right now. You will also need a speedloader, if you have the budget, get a genuine Odin (they're expensive at €50), it'll make life much easier. You could go for a clone but the one I had bought the farm on its first use.
It also boils down to your playstyle, if you use full auto a lot, stick to high caps (more sensible option to carry a lot of bbs while keeping bulk down), if you're a semi only kind of player then midcaps could make more sense because they imply an actual reload every once in a while and make things a hair more "realistic".
