In a fight Dexbird vs Dexmage, both equipped with glyph auto-bow sets:

-The buffs are good for both classes. The mage has two very powerfull buffs, defensive and offensive. The birds focus adds nice crit, evasion can save its life and sometimes even make it survive the mages nuke
-The Strategy would propably very similar, both classes kite and rely on 12m range skills + auto hits
-Both classes are able to take down their opponent within one quick combo, what makes both healing skills pretty useless

All in all its impossible to generalize about this topic, all depends on releasing the combo at the right time and on having some luck (dodges+crits). In a fight of two (equally) skilled players either one could win.