There is no specialisation so you can learn all enchants, however the 300-skill enchanting x are either drops or require reputation with certain factions. This
guide provides a full list.
The most notable ones that can be bought are:
+15 Strength (honored with Thorium Brotherhood)
+20 Spirit (honored with Thorium Brotherhood)
+22 Intellect (revered with Thorium Brotherhood)
+15 Agility (honored with Timbermaw)
+4 Mana Regeneration (honored with Argent Dawn)
+24 Healing (revered with Argent Dawn)
+15 Nature Resistance (honored with Cenarion Circle)
+15 Fire Resistance (friendly with Cenarion Circle)