LF fun set up for duo

[Ry852]

I used to play the game a while back and my girlfriend dabbled in it.

For background info I've tried
Nyx
Ash
Zephyr
And Excalibur
Out of those the only one I've really liked is Excalibur but it wasn't exactly what i was looking for in a frame.
For this duo I'm going to be trying Nidus

My girlfriend tried volt and saryn and likes Saryn for the looks but really doesn't like the abilities

What I'm looking for,  for her is a couple of frames to look up,  watch videos on and ect where the warframed excel at simplistic straight forward abilities,  and fun though obviously that is very subjective.

She wants to "be the person that blows everyone up"
To me that sounds like Ember,  but when i showed her some stuff about Ember she didn't seem very enthused. She did show some interest in Chroma, so I'm looking into how he works. 

Ideally if there is a particular frame that you think would synergies with and benefits from having Nidus along side them I'll take that into consideration.

Neither of us has ever made a frame with forma and an optimal build and all that.  What ever the recommendation the frame being fun,  or viable can't be contingent on having endgame materials, mods ect


Thanks in advance for any help