Well if you're still more interested in Tera than BnS that just means you're one of those people who like the harder combat better like I said right above your post. But regarding your complaints:
1. First you said you got each class to 20, thats not even nearly close enough to being able to feel that. Level 20 is when you JUST start getting your skill points and new skills. I'd say you need minimum of 30 to try out the class and have enough skill points to do alright, but 40 would be better.
2. Its Destroyer not Berserker here, and you said you didn't like how it felt slow and didn't have enough combos to make it feel badass with Blade & Soul Items. Again that was most likely because you were level 20 but I'd say that Destroyer is a lot more fun than Berserker in Tera. Maybe the reason you felt less "badass" is because tera is a much quicker game in terms of fight duration. So with a Berserker in Tera you can just swing your axe a bit and kill someone. But in Blade and Soul fights just aren't that short.
3. The classes that you've played probably just are the types for you, since you seem to like smoother and faster paced combat try Force Master, Assassin, Kung Fu Master. Also if you're considering the smoothness of combos in Tera better than in here then somethings just not right. Maybe you have bad ping, because that can be a big difference. If you're in EU then you can try it out with better ping next CBT because its a HUGE difference, almost 2 different games.
Otherwise you might just be slow pressing combos or just be used to Tera style where sometimes the next skill just pops up as spacebar.
Honestly I think you just need to get used to the combat because its not like other action combat games, and also LEVEL up a lot of Cheap BNS Gold. Level 20 is nowhere near enough and to save time maybe just watch videos or read about the classes so you can narrow your choice down to 1-2 classes that might suit you. Not trying to be rude but the reasons you gave just dont match up with the facts, BnS is hands down smoother and faster than Tera just go watch some Korean/Taiwan/China videos if you need to compare. There are some people who like Tera better, but not for those reasons.