New server. Need advice on topology

Hello all. I just purchased a refurbished Dell R720xd with 26 900 mb 2.5” SAS drives. This will be the largest server I’ve ever owned as far as the number of drives installed. I need some advice on how the best way to setup the drive pool. I would like to have it so it’s easily upgradable, reliable, get the most storage space. I was thinking of setting up the drives in a single pool in groups of 4 with raidz1 totaling 6 groups using 24 drives and keeping 2 as hot spares

How would this compare to running 4 groups of 6drives. If my thinking is right with the 6 groups of 4 on raid z1 if I need to expand storage I would need to replace them 4 at a time?

My current server which is out of storage space is a Dell R720 with 8 3.5” 3tb drives all in a single group of raid z2. I figured installing a second server instead of expanding into a jbod shelf.