One elf. One set of stat bonuses and special abilities. I would say Dexterity and Charisma. Most elf sub-races make me think that someone wanted an elf (or a beautiful pointy eared human that can be a snob and call it RP) AND wanted the best stats for whatever character class they intended to play.
I think elf type should be determined by location evolution primarily, although magical intervention is also a possibility.
Forest elves get forest-related qualities.
Subterranean elves get subterranean qualities (that means albino or very pale not black, depending on how much light exposure there is underground where they live and how much time they spend underground).
Sea elves get aquatic characteristics.
Maybe forest-dwelling "country folk" (wood elves) get a bit different things than forest city dwellers ("grey" elves). But, I think that's rather a stretch unless they're totally isolated geographically for a long long time.
Elves should be NPCs for my previously stated reason. I don't have an issue with there being more than one type. Just make the reasons meaningful. Evolution (including unnatural selection) over long periods of time (extremely long periods when elves are concerned) is the only explanation, other than a powerful magical effect, for differing racial traits.
As for stat bonuses... I am not a fan. I think it's more than questionable to give an entire race an intelligence bonus, a wisdom bonus, or a charisma bonus. The thing about individuals is that they're all different. Kinsey found that when he spent years collecting some sort of insect or whatever. He collected tens of thousands and said they all were unique, a result that surprised him.
I get that D&D is about the group (the party) but why be so anti-individual that you think that everyone from a specific cultural group is going to be that identical? There are going to be less intelligent, more intelligent... less wise, more wise. Less charismatic... more charismatic. Unless you're dealing with clones.
If there are no ugly or stupid elves by human standards then that can be a rule. I can see it. But, make the mechanics reflect that specifically. As I recall, 1st edition did something like this. I think the elf required minimum stats in various categories. Don't start out elves with 10s in those categories (bonuses included). 10 is average for a human, correct? Average is not beautiful, charismatic, or intelligent. It's the lack of those qualities above the norm that defines it. Instead of just bonuses with 8s I think a legal range for different races/species is more accurate to the flavor. Want all elves to be good-looking? Make 13 the minimum. I also think comeliness needs to be specifically statted as it was with the original Unearthed Arcana. Squashing a person's oration skill and things like that with their beauty is a mess.