Also, using SMW as en engine is funner IMO, because you're pretty limited and you have to think of ways to make X thing happen. If I were to pick one, I'd go with Super Mario World, because I can a lot more stuff and also, while ROMs are illegal, hacking itself isn't and SMBX was taken down by Nintendo's lawyers, as mentioned earlier. Also, there really aren't that many SMW objects to be able to make an SMW (note, I used an, because you say an Ess-Em-Double-You) styled game. X is really not a Mario game, as there are elements from Zelda and Super Metroid. SMBX can play MP3 quality music, while SMW can't. Basically, SMBX allows only that much NPCs (as they are called), while SMW can have whatever the SNES allows, which trust me, is a LOT. SMW can have sprites with thousands and thousands of different behaviours, graphics, sizes, etc. whether or not a para-koopa flies like should or does it follow you like a Phanto), their graphics and sizes. The only thing that you can change with them is some of their behaviours (i.e. SMBX allows only x amount of enemies and objects. SMBX was taken down by Nintendo itself, so I don't think it would be wise to have it. As a user who has used SMBX, let me name a few things.
