I personally liked some aspects of BF2 much more then 2142, mainly that the engineer from both sides had the same type of rocket launcher (single missile, laser guided somewhat). Also, engineers had the barrel shotgun unlockable, which I loved very much.
In BF2142, I could have gotten along fine without the ridiculously dangerous shotgun, but then they had the brilliant idea of giving both sides a very different rocket launcher each, one side had the quad-rocket which rocked and the other side had the single blue rocket which basically sucked. I came to loath that blue rocket, so hard to aim at people.
But that's all just preference really. BF2142 still wins out all around.