People like to ride on hidden missiles because in some ways it acts as a stronger sentinel force but it has a couple issues. The biggest one being that just like sentinel force he stays vulnerable for almost the entire time you see him on the screen. Like you must protect that assist ridiculously well or u risk losing it to anyone that isn’t afraid of it and knows how to get around it. Like Zero with 3 meters can just sit on level 3 and if he sees hidden missiles come out on screen just throw out level 3 and if the person tried to throw a projectile during that they get hit for decent damage and Doom dies easy because there’s like a bajillion frames where he is hittable unlike a short amount with the normal assists. The more people devise tools to get around it and punish the laggy hittable recovery the less you’ll see it be this dominating lame force.
The other issue is that some characters like Tron have projectile invincible frames on their air H which pretty much render it useless unless once she gets in. Once she gets in it cant be called or her air H will eat up the missiles as she comes down and hit both Doom and the point character for big damage. Even if a couple of the missiles get away she can stop the combo…wait for the rest of the missiles to come down and then swat the rest of the missiles away while putting the point character in another possible combo situation.
Plasma Beam overall has the best utility since it uses his M version which has 8 frames of low durability. Meaning it’ll beat Sent beam, unibeam, easily beat Magneto’s disruptah cuz that has like very little durability (its only faster than doom beam not more durable) etc. This also works as basically a full screen block string that can be used with characters that can get behind people in an instant like Wesker and Zero to create safe 50/50 cross ups into big damage. It works like Chun Li assist for blowing up advance guard and letting people get in and also lifts people up after OTG’s for more damage. He also doesn’t stay out there for a year like missiles.
command dash to where I’m just above the opponent’s head, and do a Sentsuizan (dive) right above them at about the same time the Plasma Beam connects. The Sentsuizan on its own is pretty ambiguous, and when you add the plasma beam it makes it almost impossible to tell which way to block every hit, and if even a single hit connects it goes into full combo.