ASM Disks Per Diskgroup
To avoid kernel contention, a minimum of four LUNs (Oracle ASM disks) of equal size and performance is recommended for each disk group.
Do you plan to have more than 4 disk groups? 1 TB HDD are usually faster than older 500 GB.
4 Disks Per Diskgroup
Oracle Doc 4 Disks Per Diskgroup
Oracle19c ASM Info
Oracle ASM Limits
ASMLib