I haven't played a SMT game yet, which ones do you guys recommend?

I've played both and Tales is by far the better game if only for the combat and character interaction... plus that gay shop keeper in Nocturne really creeps me out.

Shin Megami Tensei for the challenge alone. and if you are burnt out on how RPGs are usually, the SMT series nearly stands on its own.

here is an overview of the whole series up until Persona 4 got announced:

http://hg101.classicgaming.gamespy.com/megaten/megaten.htm

Persona 3: FES. Far and away the best in the series.

this is one of my fave scenes from a megaten game:

Tales.

I would, but it's on the 360, a console that I'm not planning to own. But someday probably I'll play Tales of the Abyss, and if I ever buy a Wii, Symphonia, then I'll be able to give a better analysis. But don't worry, I know Legendia is not an indicative of the quality of a Tales game, and as you said, it's not a bad game. Just a bit uninspired.

Shin Megami Tensei can be off putting to some as it is very dark, brooding, demonic, gothic, and not so innocent or for innocent people like your typical fantasy world based rpg like Tales.  However, if you prefer more mature games as I do (though not all the time -- "A good children's story should appeal equally to adults as well as to children" -- C. S. Lewis), then you will get much enjoyment out of Tensei.  However, if your mind is still very much a more innocent one, then don't go into Tensei expecting adorably cute characters, a bright colorful world, fairies, and bunny rabbits.  If you have moved from Tales to Disgaea and are ready for the next step in that direction after that or been on some other similar trajectory in your lifetime then Tensei  is for you.  If you like movies like The Exorcist and The Omen or if you are a fan of Marilyn Manson, then you will also probably enjoy it.  It is possible that the Shin Megami Tensei games actually go no farther down that path than an anime such as DeathNote.

     Personally except for Persona 1 and 2 on PS1 and a little bit of messing around with the originals on the NES and SNES, I've never really played a Tensei game.  Both Persona 1 and 2 had very poetic introductions and looked like they had the potential to be very good.  However, there was one facet of those games that prevented me from playing them and that was that they were 3d corridor crawling games like Wizardy, Might and Magic, and Oblivion, and those games make me feel queezy.  Plus, I'm not a big fan of mapping out mazes.  I've heard that Nocturne (PS2) is more like a very dark Pokemon.

     I have read quite a bit about and would really like the chance to sink my teeth into the new Tenseis -- Digital Devil Summoner, Persona 3 FES and Persona 4 especially if they are designed more like Final Fantasy and not like Oblivion.

      Another non-traditional fantasy  jrpg series that goes down a rather dark path (though reportedly the last one wasn't so dark) is the Koudelka / Shadow Hearts series.

My final analysis of this matter is that the Shin Megami Tensei series is better than the Tales series. However, the Tales series should appeal to a broader audience of people than the Tensei series.  Tales is exoteric and Tensei is esoteric.