There is little difference in choosing one over the other at the moment. I’d like to see the trade off that is in live. So here are some suggestions to change it.
The Altmer changes are for the spellcharge passive.
1000 penetration (baseline)
1000 penetration and 50 magicka regeneration after using a class ability for 6 seconds. 6 second cooldown.
5% extra enchantment potency.
Gain 325 magicka and stamina after using a class ability. 6 second cooldown.
I think all of these changes would be cool and make for a more interesting pick, not only between Altmer and Dunmer, but in general. The penetration would give more freedom with some Cp, the penetration with regen the same, but with giving you ~240 magicka back for each class ability. The enchantment potency might be too good, but it still fits with the lore (and helpful for stamina toons too! As they seem to want that for Altmer..) and lastly the magicka and stamina is both a utility and recovery passive, just for it to not be useless to a group of players.
For dunmer I’d change the magicka and stamina resource to 1750 (a bit more difference so that the choice matters) and give 150 spell damage to flame damage abilities.
This gives dunmer the cool flame damage bonus back which makes it unique, but a bit lower magicka, and missing that bit of sustain or raw power so that the trade-off is there. Honestly I cannot comprehend why no one in the balance team thought about adding the spell damage to the dunmer instead of a % as it is on live. Why did they just remove it?!