You have quite a few options to choose between when choosing which stock to put on your CZ Bren 2.
And the good news is also that you can use the same stock on all the CZ Bren 2 models: they are all compatible.
Folding stock
The advantage of folding stock is quite obvious: it gives you the option to keep your Bren more compact, easy to carry and store. Also it gives you better manipulation in tight spaces.
However for the most of the shooting, you will use it unfolded for the shoulder support that it offers.
Folding stock is also not only foldable, but also collapsible, although the collapsibility is limited.
Collapsible stock
You can also get a fully collapsible stock, or a stock adapter that allows you to use collapsible stock tube [usually with 6 positions in which you can lock the stock butt] and also gives you the optionality to choose buttstock that suits you the best, or that you already got used to from another rifle. The negative of collapsible stock is that you cannot have the stock folded, and thus the Scorpion takes more space for storage as well as for carry.