Depends on perceived needs, bro. If everyone's were the same, we'd all carry identical guns.
I like .357 SIG. However, I rarely travel with one because good carry loads and plentiful practice ammo are hard to find in that caliber on the road. Some find it a bit too snappy in recoil.
One approach is two identical pistols in each caliber, such as a Glock 17 for practice and match shooting and a Glock 31 in .357 SIG, set up with the same sights and trigger system, to take advantage of 9mm's generally lower price and greater availability. .22 conversion units and 9mm conversion kits for your .357 SIG pistols give you another option.