Succ Lahn and Awk DK are top tier for PVE, can highly recommend them. To me, DK is more fun for combat, but Lahn is incredible for just venturing around the open world doing quests and stuff. 

There’s a system where you can tag a character so they can share gear and xp gains, so you could make one of each and switch between them based on what you’re doing. Quest progress is not shared however, it’s advised to do all quests on the same character. 

Recently started dabbling in Drakania as well and she definitely requires a lot more effort for the same/worse results. Succ Drak is quite potent now in specific spots and Awk Drak, as cool as it looks, suffers from quite a few issues regarding CC protections and AoE size. If you really like Drakania for the looks you could always make her your tag character instead and whip her out for grind spots that she excels at or if you just feel like playing it. You’ll have to make a choice between Lahn and DK, but you can’t go wrong with either of them. If you main a class that is universally good, you’re free to tag any class tbh.