not which one is technically the "better game", which one do you think is more fun or would you recommend more i've never played smash of fire emblem
depends what you want really. Smash is fighting/party game that is really goddamn fun and there's not really anything else like it, but it's repetitive by nature. fire emblem is a fantastic srpg with a whole lot of fun characters.
Smash 3ds is overall a solidly executed by somewhat rushed smash game, FEA might be the smarter choice, but that's coming from my personal bias towards singleplayer experiences
Smash is a good quality fad right now, but it's still a fad. Like MK8, the online community will die down. It'll also kick back when the superior Wii U version comes out. FEA isn't dependent on an online community. Part of the fun of Smash is Smashing with friends and single player stuff can only go for as long as it can keep your interest
online will die down but... it's not like any previous Smash Bros needed online to last Though the lack fo singleplayer might do that anyways, since Smash Run is really jsut a novelty, and besides that you just multi-man classic and allstar in terms of fighting (and a meh version of target smash, an home run being the same as ever) this is THE most grindy smash bros, just to warn