well, lets give it a try
Edelgard: this is the hardest one, since she appears to be good with axes and magic.... which are kinda the opposite. Rumors say she will be a Baron, so if thats real, i would go with that. if not, probably fighter, since it retains axes and get gauntlets, and that really got me interested
Dimitri: probably paladin or soldier, depends on what soldier is promoting to. if its halberdier, then im done, if its knight.... im sad. either way, you cant go wrong with paladins, right? and since dimitri comes from a country that appears to be based around knight, paladin seems a good choice
Claude: i never wanted a rumor to be so true, couse i love mounted archers, and a FLYING ARCHER is something im really interested in seeing again. if it turns out to be not true, i will still just pick the bow knight equivalent.... did i say i love mounted archers?