*Based on what you have seen, I only have a few suggestions that you might like, but they are all good.
1.) Death Note (37.episodes)
Death Note is a "delicious" Anime with very good English dub. What I mean by delicious, is every episode hooks you in and you can't stop watching. Simply put, this is one of the best animes ever made, and anyone who tells you otherwise has questionable taste. It has a genius original story, very likable characters, and a great soundtrack that elevates the suspense of the show to another level. Now, since you are only 14, I will warn you, this show is a little darker than some other shows you have watched, but I think you are mature enough to handle it.
2.) Trigun (26.episodes)
This is a great series that was short-lived, lasting only 26 episodes, but it was a fun ride while it lasted. It's mostly a light-hearted action-comedy that has serious tones when dealing with death. Granted, it's a little dated(made in '98), but that shouldn't discourage you from checking it out. The art style has held up well of the years, and many anime enthusiest find the protagonist of the story, "Vash the Stampede," one of the greatest anime icons ever. I'll even admit, that this series had me a little teary eyed at one point, but, (shhh), don't-tell-anyone. ^_^
3.) Samurai Champloo (26.episodes)
I'm reccomending this one purely because of the action! The main characters of the story, "Mugen" and "Jin," are also popular anime icons that you should know, and for good reason, they kick ***! The story is good, the music is incredible, and the characters are memorable, but I'm not the best person to tell you why this is a cool anime, because I love it simply for the crazy-great fight sequences. Well, now that I think about it, I just told you why it is a good choice.
4.) Eureka Seven (50.episodes)
I know, I know! This is twice the amount of episodes you said you wanted, but I would be doing you a tragic disservice if I didn't at least put this show on your radar. If you watch the first 25 episodes of this, I believe you will definitly want to finish the series. Eureka Seven is my favorite all-around Anime, ever, that was a near-perfect production. It's hard to describe what it's about, but if you like sci-fi then you should check out this anime. The action, story, art design, characters, and soundtrack are all 5 Star quality.
5.) History's Strongest Disciple Kenichi (50.episodes)
I know, I did it again; it's more than 25 episodes! But this anime is a gem that most people don't know about. The action in this isn't a game changer or even the best out there, but it is solid. But it's not the the action that makes this show great; it's the fact that it's so freakin' funny! Without giving to much away, this show is about a kid who has been bullied his entire life, and finally decides to stand up for himself by learning to fight. It's kinda like the Japanese version of the Karate Kid. If you do give this one a try and you stick it out to the end, I promise you will be left satisfied.
6.) Claymore (50.episodes)
This show is cool. Claymore is the story of an organization of half-human, half-demon female demon slayers known as "Claymores." As the name suggest, these mercenaries each wield their own claymore to exterminate their monsterous prey. Now, check your prejudice judgments at the door, because this is NO girly anime. These chicks can fight! Not only do they have uniquely, leathal supernatural abilities but they use them in the most satisfyingly gorey ways. If you like your women as tough, badass killers, then you should definetly give this one a try.
*I hope you consider some of these, and, should you watch them, I hope you enjoy them. I give my personal stamp of approval on all of them. Good Luck! :P