Serious answer:
358 is more common size for bullets for sale, bullet molds, sizing dies. And if you have issues chambering them, you can size them down to 357 and give that a try. Then buy 357 bullets in the future, if that's what works best. If you try 357 bullets and they work good enough, you still won't know if 358 wouldn't work better unless you do a chamber cast.
You don't always want to limit your bullet to 1 thous over groove size in most firearms that aren't revolvers. That's not a magic formula to get the best accuracy. (And even with revolvers, a lot of shooters go way over bore size in order to adequately fill the cylinder throats, versus going 1 thous over groove.) But there are definite and immediate benefits of trying to achieve within 1 thous under leade size; less lube smoke in rifles and locked breech semiauto pistols; usually better accuracy and/or higher velocities without fouling, all else equal (if for no other reason than you'll have more of the lube on the bullet, rather than shooting out the muzzle partly burned in a cloud of smoke). Only real downside is that your ammo might not fit other guns.
So the safest/cheapest route for someone who doesn't already have chamber casting material and desire to do that is buy a small amount of 358 bullets to try. Then buy a 357 sizer, if needed, which will cost less than 500 commercial bullets (and which can be opened out to 358, if desired, in the future). Then you'll know what bullet mold or commercial bullets to buy! If you want to go straight into casting your own, 358 bullets with the correct weight for 9mm will also work in 357/38 revolvers or rifles, if you have those, too.