If we are going to talk about TSC magic vs TVD magic, I suppose TVD magic is kind of better. Because it -- well, has limits too, but TVD magic can be enhanced by quite many things, such as channeling to other witches (so far I can tell unlimited channeling, such as to 1 witch or 100 witches), to full moon, new moon, comet, elements of the nature, nature itself, amulets, talismans, etc. On the other hand TSC magic can be blocked by iron-ash mixture, and is limited to the circle. Power however, can be transfered, like in the finale Charles' mom gave her power to Charles and Dawn, and despite it should significantly reduce their individual powers, it didn't. They were as strong as they were supposed to be, so I'm not sure if that is something, like 1 makes 2, two makes 4, etc. But it shouldn't work like that. I honestly can't tell, because the show was cancelled and anything else I would say would be assumption.

But if we are talking about Cassie vs Bonnie, I'm saying Cassie would defeat Bonnie on her worst day. Because as of season 1 finale, Cassie was an advanced pro on both dark and circle magic, and her magic cannot be blocked by iron-ash mixture, as seen in 107 Masked. She practically has no weakness. If we got to see how more she would advance in magic in the 2nd, 3rd, or possibly 4th season, I can't imagine the power Cassie would possess. Like you said, Cassie showed an incredibly fast development in powers. If she had half of that in the future seasons, she would easily be stronger than Bonnie by now. 

At least that's what I think. 

PS: Keep in mind that we are discussing Cassie and Bonnie's individual powers, not channelled to anything. 

Cassie needed Diana's help to defeat their father. I am not going by what could of happened but what happened. Cassie started learning about her other side of magic season1. Bonnie learned season 4. If Bonnie started expression season 1 it would be the same fast progression in season 4 she had. 

Well, Cassie floated water drops the day she learned she's a witch. Bonnie knew all the time but couldn't float feathers before taking serious training from Grams. 

@Mgc first message

I think Expression is more useful than Cassie's enhanced dark magic. She just has better feats. And it is much ahrder in a world with vampires.

And the thing I hated about TSC is how useless everyone aside from Cassie was.

The rest of the members of the circle were weak as shit.

The "elders" didn't do anything more than fucking Sheila.

We get an Medallion with THOUSANDS of witches powers in it. Yet all it did was create some fires and ghosts.

If your not a balcoin then you suck.

@Mgc second message

Well there is a difference. Cassie had Adam's help and they were already channeling the power of the circle which means they had more help. Bonnnie was using only her own power.

Alright, maybe floating water thing was not a good example because yes, she did get help from Adam. But if memory serves, she stopped the storm and rain by herself that Faye started but neither she nor Diana could stop. 

You definitely suck when you're not a Balcoin, we agree on that :)

The elders were just regular witches, but the grandparent generation. I didn't expect them to have much significance anyway. Or maybe they were like Senior Partners, or the PTB, who stay out of the game but is known to have huge power. I can't tell. We only saw 4 elders. One of them was crazy, one was killed, another was made mentally incapacitated; but I know that Charles' mom had such great power that half of it was enough for Charles to take down a man with 6 demons.

Medallion thing is kind of vague in my mind, but if I remember correctly many many witches or dead witches - I can't recall - came after it, and it was destroyed after 1 or 2 episodes before we could see it's full strength, kinda like Bonnie's 100 dead witches, which we didn't get to see the full power it gave to Bonnie.

Don't forget her latent dark magic and circle magic helped as well :)

And I'll admit it was a good feat on her part. Granted she had more power than basically the rest of her own circle combined. But still good feat. In TVD the weakest witch we have seen manipulating a storm would be The Witch of The Five.

But they were supposed ot be wise and powerful. Only Royce and Kate ended up being strong at all TBH.

Faye's grandpa sucked and Jane only did one cool thing with a crystal. Otherwise she was a punching bag for the whole season.

And Charles mom( Kate) wasn't really that powerful. She admitted her magic was inferior to Cassie's. And Cassie could not handle even a pair of demons with her power.

The reason Charles owned them is because he basically offered them a better deal. Probably by giving them a taste of a real witch. There was no way he could injure the demons on his own.

And why didn't any other witch like Blakcwell do that if it was so easy? Becasue Blackwell needed to maintain that the hunters were a threat to them so they would assemble the skull. That is why he didn't teach them that spell. But Charles was more knowlegebale and not brainwashed. SO I don't think it meant she had a great amount of power.

That's fair though it was still a missed oppurtunity. And it also made no sense for Blackwell to ditch it. I eman does he believe something with the power of 1000's of witches won't come in handy? Or was being a balcoin witch still more stronger?