Hmm, well, I admit.. for the moment I am going in a rather basic and cheap direction when it comes to drawing programs. I have Photoshop 2 that was temporarily released on Adobe's website, and I used to have that as my go to when drawing, it was fun at some moments, but a lot of times it also felt rather clunky, and it didn't exactly help the fact I have somewhat shaky hands.. I did try Paint Tool SAI recently however, and I found it to feel far more natural and flowing, and faster and efficient, so it reignited my urge to draw again, which is awesome. Sure, there are a few things I feel annoyed about with it too, but most of the time I am very happy about using it.

I usually use sai, I like the brushes I have for shading and the way the blending can be set on them, but I just keep it how it is. Sometimes I'll need a change and move into drawing in photoshop for awhile.
I've been drawing in clip studio lately and I like that one a lot too, I just have the trial but I'm probably going to buy it and make it my main.

I use Corel Painter 2015 and I'm loving the new brush features they've added. The particle brushes are amazing.

Photoshop. It's what I started with, and it's what I'm used to.

I use Photoshop since it's the most versatile, content with SAI being used only as a sketching and inking platform, and am trying to get used to using Open Canvas 6. I tried Clip Studio Paint but thought the UI was a mess and had a hard time getting used to it.

I use Paint Tool SAI for sketch/ink and paint, and then add a bunch of color corrections and effects in Photoshop... CS2 :"D I should update my stuff.
I occasionally experiment with other softwares though.
the one I hear a lot complimented on is Krita, and it really improved a lot lately, too bad it still only runs on beafy computers D:

I use Sai, OpenCanvas and Gimp myself.

I have the full Adobe CS4 suite and have had it for a long time... so I originally did all my art in Photoshop.

Recently, however, I picked up Paint Tool SAI... and man, does it make cleaning lineart and doing block colouring freakin' easy! Heck, from the scanning process, I can pretty much be done the digital line-art and block colours... with just a mouse! It's nuts! Even coloured lineart is just a few simple clicks. MAN!

I still use Photoshop for this and that... but for the most part, I'm really liking SAI.

I used SAI for a few years and moved over to Clip Studio Paint a few months ago. I'm loving it a lot since it still has the smoothness I love about SAI with much more versatility, similar to Photoshop in that regard. I've been pretty happy with it! The only thing I really miss about SAI is the blending of the painty brushes. I can paint a lot faster and more efficiently in SAI than CSP.

Photoshop is my main tool. I tried Gimp for a while, which is a pretty nice program on its own (it has some really nice brush features), but I found that I like the flexibility that clipping layers gives me. So Photoshop.

I use Manga Studio 5! It's like SAI and photoshop had a baby and I really like it. It handles large files super well, it's a lightweight program, and I enjoy the painting brush engine and flexibility. @w@

I use Photoshop CS6 as it is the easiest to get around with so far, though I have been thinking of moving to Krita which its only downside is that it's still not properly optimized on windows, otherwise it's a step I might do in the future if they can fix performance issues and finally solve how-to-use-graphical-card-rather-than-cpu.

I use Krita. Its free and and it got nearly everything that I need. I used GIMP a long time but I hate its working space and all that window-stuff floating around. The version that trys to look like photoshop was always unstable on my pc. But Krita works fine for me.

I use SAI most of the time, since my version of Photoshop 7 does not work well with my tablet. The lines appear to be really unstable, I don't know exactly what the problem is. But with SAI, everything works well. I do use photoshop however for background designs for my character sheets and for creating brushes. :3

I like SAI myself for all the major drawing I do, with it's stability and versatility with brushes. However, when it comes to some effects like jitter, colour balance and anything geometric, I usually pop over to GIMP and use that too ^^

I use Autodesk Sketchbook Pro for a lot of my sketching and base paints.
I sometimes use Manga Studio 5 instead, when I want to do more delicate linework.
I have Paint Tool Sai and Alchemy, but I don't use them very often.
I finish all of my work in Adobe Photoshop CS5.

SAI has the best ink tool, blending, and smudging of colors I've ever seen...and Photoshop (version has changed through the years, but I used CS4 the longest), the warp tool was my best friend as young artist, it can handle massive files, and the fonts and detailed gradient layer masks are the best.

I've been using PS7 forever, but I'm starting to play around a bit with ArtRage4--bought if for $25 a while back and figured I should get some use out of it. It's very "traditional art" oriented and I've been enjoying it so far--haven't done anything large-scale with it yet as I'm still trying to get the hand of the tools. It definitely has some potential, though.

Regarding line work, I have a friend who is the lead/dev/owner of a program called 'ArtRage' of which I've given out a few copies. It's a overly accurate real media emulator, and one of the items it does exceptionally well is inking. Might want to have a squiz. (And I just realized as I was typing this that Selkiegal above has also mentioned the program. :D )