Wow....tough question....there are differences....none necessarily better or worse than another just different.
Allen is probably on average the older of the 3....it is a bedroom community that popped up 25 years ago. There is still some new construction, but my guess is that growth has peaked there. I'm guessing in Allen you would have the least aircraft noise as it is the most distant from the 3 major airports. Just like greater LA area, there is aircraft noise everywhere. Probably average age of homes is older than CV or Keller.
Keller has seen huge growth over the past 6-7 years. So lots of new homes, lots of new construction in all price points, Lots of young families, lots of youth activities....lots of new schools....still some growth pains...streets, services, etc. Aircraft noise here is from Alliance...and typically at the wrong hours for most people...since it is mostly cargo and maintenance.....Peak traffic is probably 10pm-12mid and again early AM 5-7am....or something close to that....no passenger traffic to speak of here..... the noise patterns I've seen typically are from ends of the runways.....less noise to the east and west of runways...or to the sides of the runways.......
Colleyville...on average a little higher price point than Keller or Allen. Probably on average a little older with a little higher income stats than Allen or Keller. Much closer to DFW airport ...so average aircraft noise will be higher. I've never really had people complain about aircraft noise in CV, but I'm sure it's there.
All cities have crime, but my guess is these cities are about as safe as anywhere in the metroplex.....
There are a few great resources around. I think it is best to contact your Community Resource Officer or CRO at the police department. Just call the main non-emergency number and ask to be connected to the CRO. Theyâ€™re normally very aware of the good and bad areas of the area and can normally give you local statistics. You can also check out http://www.ojp.usdoj.gov/bjs/ which provides stats based on the FBI uniform crime reports. You might also visit the FBI stats site at http://www.fbi.gov/ucr/ucr.htm#cius. Another place to checkout is http://www.Crimeweb.net .
Avg price in Allen is about $236,000, CV 502,000 and Keller 310,000,
My next question would probably be how much commute do you want. I think most people who would consider Keller would not consider Allen. Way too far apart.... Most of my clients who would consider Allen would look at McKinney, Frisco, maybe Plano. The people considering Keller....probably just look at Keller..maybe Trophy Club....maybe Grapevine...maybe Flower Mound. People who consider Colleyville, might also consider Southlake with a little higher price point.....maybe Grapevine...maybe Coppell or Flower Mound too..... again depending on what kind of commute and price range you want, you might also want to consider someplace like Lantana or Frisco.
Hope this helps....if we can be of further assistance, just ask.