First off, I think you're referring to "Pixel" rather than "raster". Also, Adobe Illustrator is a "vector-based" program.
So, going into the discussion. There's really no such thing as the "best program". It's simply a case of which one (or combination of various ones) the person is most comfortable with...which differs for different people. Keep in mind that art is more about the artist than the tool that he/she uses. "Photoshop" is nothing more than a really shiny pencil...in the hands of a skilled artist, it can do amazing things. In the hands of someone who isn't experienced with it...it'll perform the same as any other program.
Alot of us uses different programs (or combination) based on what specific style that we strive for. If you want to do matte painting, it's Painter IX all the way (although some would argue for Photoshop here as well -point relies more on the artists' skills and preferences than what is actually "better"). If you want to do inking, it's said that Illustrator and Flash is the best way to go due to it being vector based (although I, personally use Photoshop for this, another case of preferences). I've also heard Manga Studio EX works really well for inking as well...but I've never used it, myself. For comic-book style coloring/cellshading, the range is REALLY broad here...since you can use just about every single program for this however different artists will tell you different things.
As for myself, I use:
-For Painterly style -> Photoshop + Painter
-Inking -> Photoshop
-Cellshade -> Photoshop + Painter
-Retouching -> Photoshop
I was asking your opinion, not what's really "best".
And I meant vector, lol, sorry. XD
I use only Paint Shop Pro, which you can usually get version 8 on ebay for about 20 bucks. It does so many things, so well, and it isn't confusing as heck like Photoshop is. (to me)
I don't use vectors because I suck at them. But the whole program is quite good.
Most professional comic artists use a combination of Photoshop, PSP, and Vue/Maya and whatever else they get their hands on. Each has something of value.
But myself, I've stripped Photoshop off my hard drive twice, I hate it to death. PSP all the way baby 
If you're doing web artwork, stuff for viewing and less in the way of pro print-job things, PSP is much better than Photoshop. For anything more complicated or requiring (for whatever reason) a million layers or something, Photoshop is good.
... Why no, I never use layers, either. I've never had to.
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Repurposed
Yeah, I actually started out with PSP too earlier on, too. It's much more user-friendly than Photoshop and a good way to practice on without being overwhelmed by the complexicity of Photoshop.
I switch fom Corel Photo Paint to PSP. Really like Photo paint and I was used to it. Took awhile to get used to PSP but getting there. My only gripe is the lack of really good books on PSP techniques for the type of stuff I do which is postwork of non-photographic work. Adding effects and such.
I love Photoshop, but yeah the learning curve from PSP which I started on is immense! PSP does vector work too, I suppose I'd switch back if I hadn't already gotten use to Photoshop.
Corel Painter can't be beat for having much more versatility in that painterly feel to work. But like any program it's the user and not the software.
Recently I've enjoyed the demos of Open Canvas, which is really affordable, and to me is like a Photoshop Lite. It's strictly for CG work, because it's stripped down to brushes, erasers, colors, layers, etc... none of that photo manipulation crap that Photoshop is loaded heavily with...
Also good is Comic Works for just line and inking, the company makes a coloring version, but I found it clunky.
for vector art, I was a big fan of Corel Draw for the longest time.
But... along came Macromedia Fireworks, which is kinda stripped down, but it does what it does very well. You can tell it's a web graphic program, designed to interface with dreamweaver, flash, shockwave, etc etc.
These days, I do all my dabbling in GIMP, Poser 5, Bryce, and the occasional nostalgic foray into POV-Ray. But, I'm not a painter. I'm more of an architect... connect the dots, apply textures, set up cameras, that sort of thing.
All the post-production work I leave to the pros.
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Open Canvas, or you'll see on deviantart OC, apparently is the cat's meow for some folks. I can't believe the beautiful results you get out of that program.
*corel draw* die a horrible death. I hate corel and all things related to it. GAH! lol yes there's a reason for that
Please read my FEAR/Portal/HalfLife Fan Fiction!
Repurposed
For Vector?
Illustrator, hands down.
For art in general?
It really doesn't matter, I've seen people do amazing things with MSPaint. The program will not make you a better artist. It's how the artist uses the program. After all, Photoshop, Painter, OpenCanvas, are just mediums to which artists create work by.
I go between programs like many of my friends. Illustrator for inks, Photoshop for base colors and shading, Painter for painterly effects, back to Photoshop. My computer LOVES me when I open all three programs at once. Heh.
Adobe Illustrator, Paintshop Pro, etc. Like raster image programs. I'm wondering which of them you guys think is the best.