I don't think any of the other alts are really considered store of value.
Bitcoin itself isn't even a great store of value, and I say that because there's a good chance that if you buy it today it could drop in price tomorrow--and then you've obviously
lost value. Of course that's true of many investments, but bitcoin is a lot less stable than many of them. If you buy an ounce of gold or silver, there's a greater chance that you won't lose much value in the short term. If you buy some index funds, you probably won't lose money in the long-term (depending on when you buy, of course). Bitcoin is just way too volatile to be a traditional store of value. A great speculative instrument, yes, but it's nowhere near being a safe haven asset.
And altcoins? They're generally even more volatile and have less liquid markets.
If the transaction fees go back to the $50/transaction then most likely people will buy Bitcoin once and keep it stored and then sell it a few months/years later paying the expensive transaction fee only once.
Ugh. I remember the last time fees got that high, and it was ridiculous. One of the great things about altcoins is that fees are much less and confirmation times are much quicker. That doesn't make them better stores of value, though, because as I said they're usually more volatile than bitcoin itself.
Strictly speaking, every thing (digital or physical) can function as store of value, the difference between the store of values is how effective they are doing and what you want them to do.
I actually like Dogecoin too with how friendly the community is, plus the fact that Dogecoin throughout the years has been the second most used coin after Bitcoin when it comes to micro transactions.
The first part of what you wrote is kind of what I'm trying to say. I just don't think if you want an alternative to keeping your money under your mattress that you'd choose bitcoin--or any altcoins--to do that with.
As to the second part, doge has been pretty stable price-wise, except for the fact that it's denominated in bitcoin. I think it does fluctuate fiat-wise pretty drastically when the price of bitcoin goes haywire.