Only characters I've spent spent a good amount of time with and playing matches with are Cybernetic Kano, Kenjutsu Kenshi, Slasher Jason, and Hellfire Scorpion.
Kano's got super easy combos. 1,1,2, laser, 1,1,2, ball does like 29% and there's absolutely no timing required. The only thing I have trouble getting consistently is hitting 1, 1, 2 after two reps of b3, 1, 2 in the corner. There are, however, much easier options that net only 1-2% less damage. It's really easy to pressure opponents if they don't know the matchup. If they do, however, Kano needs to work a lot harder to open you up. He needs to bait and punish to get damage. I consider him easy to learn with tools that are easy to understand and utilize effectively... minus upball and up laser.
Slasher Jason has just ever so slightly harder combos, but not by any means ddifficult. He gets what I think is 37% meterless off the low overhead string easily. Far as I know he doesn't have any tight links that are practical/viable. Slasher Jason is also easy to block, but at least he has a overhead to check with. Overall he's even easier to use than Kano because of his damage.
Hellfire Scorpion has the standard teleport and spear combos that deal good damage and are real easy. Linking after Flame Aura can be difficult, but he has fireball cancels to keep himself safe. This is where I find Scorpion difficult. I'm not great at hit confirming, and appropriately confirming into a fireball cancel or teleport with consistency is pretty hard for me. Scorpion is definitely harder on a technical level than Kano and Jason.
Kenjutsu Kenshi has the hardest BnB out of the the four. Linking a 1 after d,b,1 is so inconsistent for me. Sometimes I get it 20 times in a row, and then I'll drop it 20 times. I know I'm always pressing it too early. The height that you gotta hit the 1 is so low to the ground it seems. Kenjutsu has really great tools though and a vortex. Some of his execution is pretty high which makes him "difficult", but I feel he is easier to use and win as.
I also spent some time with Tanya and she definitely seemed the most execution heavy of the cast.