I think it depends on what you like more. From a practical perspective (cost), it would be better to have fewer fireams and more ammunition. But I can't say that I am always practical and some guns are purchased with the intention of never shooting them. I don't even have ammo for some of the firearms I own. Don't really care as there is plenty of other choices with ammo.
The other side of the coin is more firearms and less ammo... For the average shooter and I would question if they are a "shooter" at all, they don't need more than a couple boxes of ammo for a particular firearm as it becomes a lifetime supply.
Then there is the occasional shooter. I guess of late I fall into this catagory. I have been doing other activities instead of shooting. It is not money. It's time and interest. So, I have ammo for the firearms I shoot, ammo in abundance for my 22's, but less for most of the others.
There is the SHTF argument... That is a scenario that is likely not to happen in the US on a long term basis. Some make extensive preparations and have an abundance of ammo and firearms because of this potential situation. Me... I think it's good to be prepared for shortages, but more than likely a few hundred rounds of ammo is all you will ever need in a real SHTF even. I have enough for any reasonable future event short of a zombie attack that will last forever.