Bomb King - BK's kit is almost perfect in my point of view, his main problem are his cards, that make his mistakes way less punishable. Royal Subjects and Royal Decree make missing bombs not that big of a deal and King's New Cloak and King's Court significantly increase his chances of getting out of a bad position.
Cassie - Her kit is simple, is not unique and its easy to unbalance, however it is really fun to play. Megaton and Summersault paired together make her really annoying to kill, if one one these wasn't there Cassie would feel just as good to play as but not that frustrating to play against.
Drogoz - Drogoz is really map dependent and is the champion with most counters in the entire game, while not being unstoppable in the maps he is good in. You can come up with a lot of playstyles due to his 3 talents being good and fun at the same time.
Imani - Only A- because of her kit idea, that is really creative: have 2 stances, use the better one depending on the circumstance. The problem is, in practice, you pick one stance and use it for the whole game depending on which patch you are playing. The player should be rewarded by changing stances, so making they more distinct from each other would be key, like making ice better for tank melting and fire for fighting flanks or making ice better at close range and fire for long range, for example.
Dredge - He is a design mess, its like they had a bunch of ideas and they just mashed them all in one champion. His portals are near useless without cards since he takes ages to reposition due to how slow Dredge is and how long the portals take to work. The worse part is that even if you manage to place the portals correctly they get easily camped. The reload on his basic is a cool idea but its completely useless by base, but makes Scuttle such cancer in closed maps like Ice Mines, and its not like the player feels rewarded for using it correctly, since you are only spamming angles and hoping for you team to sandwich them because they cant go through your spam. The fact that 2 out of 3 talents encourage you not to use your weapon as main source of damage when his weapon is the best part of his kit also makes him more of a mess. The only way i see of saving dredge is a soft rework, like they did with Skye and Sha Lin.
Kinessa - Snipers shouldn't be in this game, but she is higher than Strix because she is more interesting due to her teleport and the basic without the scope, sadly the unscoped weapon was always bad. My biggest complain about her is her ult, since she can ult and instantly get a kill on any full hp squishy with no haven.