Clip Studio Paint, hands down. (Formerly Manga Studio, I think?) It was a little difficult to get used to it after having used Photoshop 7 and Paint Tool SAI for so long, but by now it feels like a perfect combination of the two with all the tools I need...and lots more. Paneling is quick and easy, the text tool (that Paint Tool SAI was lacking last time I used it) is quite convenient and the available brushes and effect lines are another huge plus.
As someone who prefers making full color comics over black and white screentone style, all the usual pen/brush settings that other programs have and additional options like saving color palettes have become indispensable to me. It was a coincidence that I ended up buying CSP a little over a year ago, and I'm honestly so glad I did. It probably doesn't work for everyone, but I do highly recommend trying it--used to think it felt "weird," now I feel like I never want to use any other drawing software for comics/manga again.