WY1007 needs be fermented near lager temps for best results. 56-58 degrees (even as cool as 54). It tends to throw some odd flavors otherwise.
WLP029 is a very nice kolsch yeast that will give you a more true kolsch flavor. It is a little easier to work with than the Wyeast kolsch yeast (2656) as it drops clearer with out as much effort though perhaps the 2656 has more "wine-like" character which I associate with a good kolsch yeast. Both WY and WL kolsch strains ferment well in high 50's/low 60's.
Wy1007 is very close to lager flavor and will not contribute this "kolschy" flavor to the beer. That said, it is very easy to get to drop clear. I use Wy1007 about 1-2 times a week and it is a very nice strain. Out of any ale strain WY1007 is the closest to a "lagerish" flavor. It is extremely clean.
With any of the three strains you will most likely need to filter or fine to get the beer to drop brilliantly clear. The photo in my avatar is of a kolsch brewed with WLP029 and fined with gelatin. For Wy1007 biofine clear A3 is extremely effective. Cold and time will work but I have always found that fining is a must if you want to turn around in a decent time.
Cologne and Dusseldorf have a pretty good rivalry over Alt and Kolsch about which one is better. I agree you can make a decent kolsch with an Alt yeast but the little German boy in me still wants to scream "NO!"