I love Raiden and I have to confess that I never liked any of the home ports. Raiden may not have broken any molds in gameplay, but it was one of the more graphically intense shooters of the time, what with tanks leaving scars on the land and the way helicopters and such exploded. Further, some of the bosses were well animated. Raiden also had some fantastic sound effects that just didn't translate well to the consoles, like the bassy bomb explosion. I felt like Raiden was the epitome of that particular style of shooter, at least until Raiden II came out. Now that it has been pointed out, I do see clearly the debt owed to Tiger Heli. I really enjoyed that title in the arcade as well, and this is another case where the console ports just didn't feel compelling to me.
So I guess this makes me an outlier here. I love the game and I hate all the console ports (save the PS version).