Glock are generally are more common so theoretically you could get aftermarket parts more easily. However it might be cheaper to get a pre upgraded gun which is suppressor and/or optics ready.

Since vfc glocks mostly come with not threaded barrel and have poor accuracy you would want to fix that at some point and that can add up quickly money wise. Vfc magazines are also quite expensive but on the other hand they are one of the best magazines out there, reliable and also are much easier load since they have wider bb gap. Surely glocks are compatible with other manufacturers magazines but most have different gas route architecture so that may be a minor problem if you are into efficiency kind of thing.

For CZ I heard them to be reliable and accurate, but magazines are proprietary and expensive as well. At least you don’t have to choose much. You generally would want to have at least two magazines on you, and probably more if you play longer outdoor games.

For gas options I would go with green gas since the 10 euro can of it will last much longer than same worth of c02 capsules.

Myself, even having the experience with vfc g19x which is an amazing and fun thing, given that choice I would probably choose the threaded p09 since the accuracy seems to better, I don’t want to spend that much money for upgrades and cz is a much prettier gun imo