The EA and Shadowmeld are racials with different areas of usage, and I'm hoping that you realise that by comparing them you are metaphorically comparing apples and oranges, although they both undeniably fall under the category 'racial abilities'.
However, to stick to the sub-topic, how should a Rogue be expected to stick on a Druid in Travel Form with opponent D being, say a Mage, a Shaman and a Priest?
You have to work around the following spells:
Frost Nova (Instant, affects multiple targets, source: Mage)
Frostbolt (R1 is, say, a 1sec cast, source: Mage)
Polymorph (1.5sec cast, source: Mage)
Earthbind Totem (Instant, affects multiple targets, source: Shaman)
Entangling Roots (1.5sec cast, source: Druid)
Nature's Grasp (Instant, source: Druid)
Psychic Scream (Instant, source: Priest)
- I might have forgotten some spell -
As a Gnome, you have 3 ways to gain ground from a CC:
EA, Trinket, Sprint.
To apply a new CC/snare on you might take all from 0 to 3 seconds (0 for EB or a Nova intended for a second target, alternatively pre-emptive casting - 3 for the Mage and Shaman turning to another target)
What you have a benefit from is the +2% Arcane avoidance, but any sane Mage would be above 6% Hit.
As a Night Elf, you also have 3 ways of gaining ground/avoiding a CC:
Shadowmeld, Trinket, Sprint.
The same ways of reapplying a snare or CC effect goes for a Night Elf.
Although Shadowmeld can be used only when standing still, Shadowmeld can be used for other purposes as well, plus that the stealth-gain gives you an edge vs. other stealthers(bar Humans for stealth-detection). On top of this, a Night Elf has a higher avoidance in general versus physical moves and Nature-spells.
I'd say Night Elf > Gnome.