https://www.youtube.com/watch?v=SDnKE5J7ki8
Dude that's actually a story that brings out my feels. I don't want to be in a community where people switch mains because they're tired of losing! I chose Falcon when I started playing because I loved Falcon without knowledge of the potential he had. So I may have chosen fairly well, but my friend, after several main switches, chose Sheik.
Sheik is, in my opinion, the Devil incarnate. My friend learned how to downthrow techchase into dash attack, Ftilt, then FAir, and that was it. My poor, underdeveloped Falcon was cooked. I would have rather have played Mango's Fox and gotten stomped in an awesome way than that basic level of techskill Sheik my friend had seemingly pulled from nowhere that beat me in the lamest, most distasteful matches I have ever witnessed, let alone be a part of. I lost to him probably over 200 times before I caved in and tried Fox against him. I felt guilty after I started to beat him, but I knew that I would never switch over to 20XX. Sure, I think everyone should have a pocket Fox, but Falcon is my favorite character and I believe in him. Now, I don't want to preach about some "heart of the cards" bull**** and stuff but I think every Melee character, no matter how bad, can find a way. Even though you say you don't play Melee much anymore, PM's Yoshi is still really good as you commented. After all, because my practice partner switched to Sheik and was able to turn grabs into death, I learned some of my most important lessons about spacing, safe approaches, and capitalization. Eventually, because he had a soul, he switched from Sheik to Falco (yay, another one of Falcon's tough matchups), but that Sheik and the memories it burned into my mind still looms over my head. Of course, it's less scary now that I figured out how to dash dance short hop knee, but I digress.
In conclusion, you don't have to sell out to win at Melee. I know this may sound foolish or cheesy, but I really love low all the characters, even Sheik. After all, you have to face your demons to master them. Marth, as it sounds to me, sucked the fun out of playing Melee for you because you got tired of swinging a sword at your friend's characters until they went away. That sucks! I get it! So did my friend when he switched off Sheik, as he saw her as what I refer to as a "cookie cutter" character to him, or one that needs to be played in a very specific, "cookie cutter", assembly line fashion in order to win. Now, Melee is a great enough game to prevent TRUE cookie cutters from existing, but some, it would seem, come close. If you don't like Marth, keep playing Yoshi. I linked a video above that you may have already seen, It's aMSa beating M2K with Yoshi using hard work and character specific techskill that he'd worked on for a while. Why would he do this, not playing any other character, and opting for a character just above the F tier level?
Because he loves the character. He has so much fun playing that Red Yoshi that he couldn't dream of playing another main.
And in the end, isn't having fun what it's all about? Just my 2 cents, hope i could expose you to some new ideas.