Wich class shall I play?

Hello there.
No, this is not a "what class is the best?!" threat. I just need a little help for my decision.
I love each of the classes, the Commando, the Engineer and the Operative, but I got no time to play each class to the max Lv.
So I wanna focus just on one of them and it would be nice, if YOU could help me.
Just tell me wich class you love and why. Try to think as a salesman who wanna sell me his "class".
You may also give me some other reasons, like "Hm... we got enough Commandos, what we really need is an Engineer!" (just for an example).
Okay, I hope you can help me :)

Now I will ad some of my thoughts and experiences of the classes (played ~ Lv 27). You may skip this, if you want to ;)

Commando:
I Love the look of the Com. and his skills. A heavy armored guy, who run into the mobs and AOE the sh*t out of them! Stomp them, kill them and laugh at theire dmg.
Okay, you have to eat packs like candy, but it's still fun to play.

Operativ:
Ah, no one got more style than an Op. Double guns for double succsess. Activate you buffs and use your skills and look at the healthbar of the mob, melting away like ice in the sun.
Okay, you can beat ONE mob with no sweat, but you will run like a coward if you have to face a crowd of mobs ^^".

Engineer:
Yeah, use your Power-Gloves and burn you enemys with you lightning! Kill them them and feel like Iron Man.
Well, your damage is not that good, compared to the Op. and all the Coms will laugh at your armor, but who cares? Use your heal and relax while you kill the mobs, even if it will take its time.
You can also revive your teammates, if sh*t gets serious.

These are just my thoughts. Feel free to comment.
If you find any mistakes, you may keep them and use them for your next topic ;)

Greetings

2L8