the thing to remember with chinese is that it isn't the main [the vegetable/pork.chicken/beef/shrimp] that makes the big impact, it's the sauce and the add ins. i mean, isn't chow mein the one that has the crunchy wonton noodles mixed in? or is that chow fun? either way you want to avoid the crispy and crunchy "noodles" that come in a dish that already has noodles in it. and you want to try and find the lightest sauce of the bunch that you happen to like. those are the keys.
take a look at pei wei's info for a good example of this. the difference between the calories in beef [typically the highest cal] and shrimp [typically the lowest cal] is less than 100 cals per dish and portion. whereas the difference between the ginger broccoli and the lo mein is much greater. the ginger broccoli shrimp is 190 cals per serving, while the shrimp lo mein is 520 cals per serving. steak and chicken in the lo mein will run you 540-560, while steak and chicken in the ginger broccoli will run you 260-290. and just to round it out the vegetables and tofu in the ginger broccoli runs 280 while the lo mein runs 550. www.peiwei.com/downloads/PeiWei_Nutritiona
and that's what i am drawing those numbers from. the prep makes a little more difference that which main you choose.