So... I'm on a Mac for one thing. I have been using Paint Tool SAI for over a year(a fanmade version that doesn't work with pen pressure) just for laughs and doodles. Now I'd like to get a new, better software and perhaps take art more seriously. I have the option of running Bootcamp on my Macbook Pro and purchasing the real SAI for 69USD, or switching permanently to a Macbook Air that has Adobe Illustrator CS6 on it. I can easily transfer my information and loads of crap to the Macbook Air.

Illustrator feels great, feels better than SAI. It does have some weird glitches though, and doesn't work as straightforwardly as SAI does. The interface is all muddled up, and the color box isn't very big, and to get the exact color you want you have to be really accurate, or keep trying again. Also has some interesting brushes that SAI doesn't have, good to experiment with.

SAI works great, ultimately the perfect thing in mind. I've been told however that Bootcamp runs slowly on Macs, and drawing is no exception(let alone Skyrim for PC, damn). Very easy interface, everything within reach. Giant color wheel, every single time I find the right color I want within the first try.

Also keep in mind I'm choosing between an almost brand new superfast Macbook Air and a 3 year old superslow fried-network-card wanky-sound-system Macbook Pro that has sentimental value.

So go ahead and give your opinion. My opinions could seem a bit biased in a way, seeing as I've used SAI for a long time and Illustrator for barely a day. Here it would seem that SAI is the ultimate decision, but the one convincing me to switch to Illustrator is acting like SAI is a piece of crap, and I'm a bit doubtful. Clonk me if the answer is clear as black and white.

I'm not sure if you're talking about the swatch panel in illustrator or the actual color pallete but I know you can increase the sizes. As for brushes for illustrator, you can make your own as well as download a variety of user brushes off the internet.

Because illustrator is a vector based program, it will run relatively smooth depending on what you're using in it. (No gradient meshes or 3d stuff and you should be fine on an old computer) The second you bring in a real/rastered image, its going to start lengthening save times.