I just got a eshop that I have ordered and wanted to get something to play on my 3ds.

There is a current sale on both EO4 and EOU. They are available for only 15$!

I played both demos. I did enjoy EO4 demo way more since it was way longer with more exploration and the ability to choose u classes, but EOU demo was so linear, but thats due to the fact that it has a story that u must follow in the demo and it also has a casual mode that wasnt available in the demo.

I saw people online saying EO4 is way more challenging and overall better in gameplay, is that true? It was challenging in the demo, but not frustrating by any means? So what should i do? Will someone end this misery :P ?

P.S I have never played an Etrian odyssey game, but I am a huge RPGs fan.

Ask noname or Rol...

Millennium Girl is a remake of the first one, so that would probably be the best place to start. You can choose to play the classic way with very little to no story and you build your own characters, or you can play the new story mode which gives you a well rounded team of characters and builds a normal RPG-like story around them.

If you want any kind of story, MG. If you are in it for pure DRPG goodness, IV.

Unless you're possessed by a desire to complete all games in a series, I'd recommend getting Etrian Odyssey IV. Generally found IV more balanced in skill layout. The ability to customize equipment is another point I'd give IV.

Get IV. Untold does some interesting stuff and has a more coherent story but the gameplay and generally world are superior in IV. The series on a whole though is very atypical for a JRPG, ignoring character art. A bit more in common with classic WRPG

If wou've never played the series, MG. If you have played, I suppose IV would be fine, but I have only played MG.

I'd suggest 4 since it's the superior game. The story for MG isn't really great so there's no point in playing it except for the exclusive story items/classes.
and for my past experience I've played all the EO games

edit: also the demo for EO:U is really bad, they put less of a emphasis on the story after the demo ends. EO:U is also more closer to the classic where you go from level to level instead from dungeon to dungeon.

tip - make sure you have 2-3 ariadne theads at all times

I can recommend EO:IV it was hard as hell be its a great game overall.