Asking in a specific reddit for a game which people prefer, stupid, as you'll get the answer you expect, one favoring the game the reddit is about.
An honest answer? Blade and Soul has been out three years overseas, and we aren't getting all the content, they are phasing it in slowly with Cheap Blade And Soul Gold. How slowly, we don't know yet, but it's annoying having to wait three years to even get the game announced, and then wonder what they really need to "beta test" besides translations. BDO just came out overseas, and they are committed to getting it out here too. Of course it has less content, and not as "polished", it's newer, three years newer.
BDO's character creator blows this out of the water, not even a fair fight. Though the classes are locked to gender and race, which some people hate, but they have similar classes of the opposite sex and are adding more often.
Here's the thing though, you can play both right now if you are really curious, though if you don't understand Korean (or other language it's available in) the story and some aspects will be lost on you, and you can make you own mind up. Blade and Soul is closer to Tera than it is Black Desert though.
Keep in mind, games may look grindy in the eastern market, but once they're localized for western audiences, some of that goes away. Eastern players/publishers seem to like that model. I'm in no way saying BDO won't be grindy when it hits western markets, but I'm confident it will be significantly less.
I played both and I kind of like both, although my experience in BDO is extremely limited. What I like about BnS is that it's not typical Korean MMO, it's more like an adventure that you can take with your friends. It doesn't force you into the standard Korean MMO grindfest. You just indulge the awesome fights and the story without too much concern about farming the Blade & Soul Gold, exp, and the best gear. But you still can if you want to.
BDO is different. It's the sandbox MMO where you build your own adventure, but you have to know stuff in order to do it. The game won't lead you by the hand and show you its best parts, it will just throw you in the middle of the unknown possibilities and it's up to you to find things that are interesting to you. What I didn't like about BDO is that developers REALLY like to use the icon system for everything and there are different icons every time and the player is just expected to understand what they mean. I don't know, maybe I'm dumb, but I didn't understand half of the icons until someone told me what they meant. Otherwise it felt like being stranded in the mall in Japan.