I don't actively discourage or encourage any particular races, though, I do try and make it clear what the rules within my game are regarding racial cultural values and roleplaying guidelines - while stressing they can play against type (hey, want to play an axe-crazy deva? fine with me). However, if it starts to look like everyone's the same race I start to try and encourage variety. So far it's worked alright and only two people in the group are the same race.
Incidentally enough, they're both tieflings. So I think it's fair to say devil-childs have some traction. For that matter, they've had traction since 2e it's just that they've only become core recently. I can see why. There's something indisputably (okay, not indisputably) cool about the scions of demonic forces who struggle to overcome the devil within. After all, Merlin's whole backstory runs on this concept in most iterations of the character.
As for dragonborn - they seem to be accepted among my group. I don't have any players with the race but I don't have any halflings, half-orcs, half-elves, devas, shifters, or goliaths either. There is a major dragonborn NPC though and nobody throws a fit about him. Contrastly, they seem to think it's awesome when he uses his breath weapon.
Granted - most of my players are newbies (with one exception who last played D&D when it was 1e AD&D) so they're not as attached to the old races as alot of players are. But I think it's fair to say that dragonborn and tieflings were successful additions to core D&D - which seems to be what everybody else is saying anyway.