Well.....I have to say up front, I really love Knott's. I do not like Magic Mountain, personally. Too hot, too fast of rides. For me.
Neither would I like to do on a weekend. Knott's has so many special offers, on the weekends it is usually crowded {right folks? Or at least after 3 or 4 when the price drops?}.
I like the feels of Knott's. The history of it really pulls me in. If you've never taken the kids, if you do decide to go, it might be a good idea to research it. Samuel and Cordelia Knott, their history, the history of Knott's itself, it is really fascinating. Inside the park, you can talk about the buildings there, some are authentic and trasferred to the park. The awards some of the rides have won, and, what different things mean in our history. Even the train ride, that is fun. Don't tell them, but they get robbed!! Funny to watch people who've never been on it before.
Mystery Lodge, I like a lot. I admit, it always tears me up. Okay, but I'm a girl so I don't want to hear any grief over that one.....
An old time photo won't cost an arm and a leg, either.
The rides, they depend upon what you want to do. So, I can't really say about those. Wait, the only thing I will say, as I feel I must, Ghost Rider scared the crap outta me. So, I stick to the more tame rides these days.
One thing that both KBF and MM have in common is that they both have water parks.
KBF has a hotel within walking distance, check for specials, sometimes they offer a room with tickets for both parks as well as breakfast. I like that you can walk and it really isn't too far.
I hope whatever you decide you have fun.
{oh, and you can go to Sonic Burgers and the Disney Warehouse, too!}