For me its two elements that draw me in. The story surrounding the fight and the fight itself. Both are needed to create a damn good fight in my eyes, although I've seen some cases where one takes priority over the other and are able to succeed. Im only gonna focus on the technically aspect of the fight scenes here, since I have a little more to say on that front.
In my opinion, a good fight scene is one that can easily be understood. Meaning that I know what's happening without having to squint. Part of it comes from flow of course but I think another part of it comes from the drawing itself. To me, I think the simpler and less detailed the drawing, the easier it is to understand. Too much detail, especially if its a manga which is enterally in greyscale, really hampers my enjoyment because while it looks good, I don't know what the hell is going on because its in black and white. Its part of the reason why I love Dragon Ball fights so much. And is what I want to apply to my own series once I can start drawing action scenes.
One last thing I'll add is that paneling and drawing action scenes are so much fun. The fast and kinetic movements really pull me into what Im drawing and I'll usually end up finishing action pages faster than a page with characters just talking.