If you're buying modern phones and expect the charger to also be used with your future phone, I'd look for a USB PD capable power supply with PPS support. (Edit

If you're buying modern phones and expect the charger to also be used with your future phone, I'd look for a USB PD capable power supply with PPS support. (Edit: Many of the phone makers that are listed as having proprietary technologies support PD on newer phones. Since the EU mandates USB PD, I would expect the vast majority of new devices to support it at least well enough that you won't need anything else.) Rather than 10 of a given charger, consider a smaller number of GaN chargers with multiple ports, but be aware that many of the "smart" ones will reset all ports if any port is reconnected or renegotiates. I have a "smart" charger capable of outputting 100 W on one port or some mix of wattages on multiple ports (mainly for travel), and a "dumb" multi-port charger that I use both for slow charging of phones and for powering IoT devices that I don't want to be reset. The latter simply has multiple USB-A ports, which lets me charge almost anything - either with an A-to-C cable, or A-to-whatever-that-device-needs (either Micro-USB, Mini-USB, or something proprietary).