Best Second Profession For Elemantalist

Elementalists combine well with any of the other pure spellcasting professions. With Energy Storage, you will always have plenty of energy to cast pretty much any spell you want at any time you want. Elementalists are a bit lacking in the healing department though, so perhaps Elementalist/Monk would be easiest to start off with. You do get the option to change your secondary later in the game though, so if E/Mo doesn't work out for you you won't be forced to stick with it for the character's whole game career

El/Mo - definitely.

E/Me is good when you get the echo skills, then you can really cause some pain.

I ♥ E/Me. It's what I use on my most-played character. While (from what I've read, anyway) a lot of people don't seem to like primary mesmers in PvE (although I've enjoyed my Me/N) they tend to have skills that are really useful as a secondary class-- like the awesome interrupts. And remember that any skill you get can be passed on to heroes when needed.

I definitely wouldn't recommend going for a melee class like a warrior. Elementalist armor isn't built for that.

E/W can be good, not for meleeing but rather for defensive shouts/stances as they're much harder to remove than enchantments.
however both E/Mo and E/Me are much more popular, and if you ask me E/x is good enough, I usually dont have room for non Ele skills on my Ele bar anyway...

E/Mo for the support it can provide.
E/Me with echo's is pretty meh, as it uses A LOT of energy and tbh it's not that effective.

Well i survive with a full ele build xD

I say go for the E/Mo while you are ranking up and learning the game. Later, you can switch to E/Me for echo nuking if you want to do that.

I think this is the best advice to be given.
I started out as E/Mo at first too (when only prophecies was on the shelves) until I gathered all Skills for E and Mo on it and then went E/Me and those are really the best.
So far I've gotten 4 full profs unlocked on my Ele.