* It's not like any other edition.
* High level characters don't get better saves automatically, making saving throws disproportionately difficult at high levels.
* Too many saving throws, and not enough reason to make the distinction.
* Some saving throws are simply better than others, although the "feat tax" is always the same.
I happen to like the general idea of "ability saving throws", specially in 5th edition, where abilities are meant to take a central role, but I do agree that the implementation has some problems. Fixing most of them is very easy. For example, you can:
* Give proficiency in all saves to everybody.
* Give proficiency in all saves to everybody, and advantage to those that would be proficient.
* Add half proficiency bonus if you don't have proficiency.
The good thing about all this solutions is that saving throws still differ a lot from character to character, because they are also based on abilities. The first one is probably the easiest.
My particular fix involves using Fortitude/Reflex/Will, but not quite like 3e and 4e. Instead, I would replace the "Resilient" feat for this three feats:
You are fit and able to endure great physical stress. You gain the following benefits:
* Increase your Strength or Constitution by 1, to a maximum of 20.
* You gain proficiency in saving throws using Strength and in saving throws using Constitution.
You are quick to think and to get out of the way. You gain the following benefits:
* Increase your Dexterity or Intelligence by 1, to a maximum of 20.
* You gain proficiency in saving throws using Dexterity and in saving throws using Intelligence.
You have a strong personality and amazing willpower. You gain the following benefits:
* Increase your Wisdom or Charisma by 1, to a maximum of 20.
* You gain proficiency in saving throws using Wisdom and in saving throws using Charisma.
|Source: Fire and Ice - 1983|
What about classes that have different combinations of Saving Throws? Just let them choose. For example, the paladin gets Will or Fortitude. Or just Will, since Charisma is the main ability.
What about monsters? You can use them as they are. There is no problem in monsters using different rules than characters. To be honest, though, monster's saving throws don't seem to make much sense right now. Why does the Death Knight is proficient in Dexterity ST? Maybe Will would be enough.
What if I don't want feat taxes, or don't use feats at all? Just let them have the proficiency the first time they raise an ability after first level. For example, the first time the Fighter raises Wisdom after first level he gets proficiency in Wisdom and Charisma saving throws.