Of the four "major" providers, T-Mobile ranks a far 4th in terms of coverage. Since you have a phone (RAZR) that has a very good internal antenna, by design, my thoughts are that either the buildings in the city are blocking your signal or the area is saturated with users and T-Mobile either does not have enough towers and/or is not partnering with Cingular in your area to get you more coverage. Without that specific information, I can tell you that if you are in the city in the eastern part of the US, you will most likely get the best coverage from Verizon. This is their "home" territory and they have built it up quite nicely.
If you are in the West, you might want to try Sprint or Cingular and in the South, Cingular then Sprint and Verizon. It's really based on the coverage and the number of towers, since if you have always had this problem with your RAZR phone, then it is most likely the carrier. All four providers will tell you that they have the fewest complaints and several have done "independent" surveys that they pass off as unbiased, but since they pay for the surveys, they are rarely unbiased. In general, I would have to say that Verizon has the least amount of customer complaints. If you only need to use your phone in the US and their coverage is good in your area, then they are a good choice.
If you need to be able to take your phone abroad, then I would suggest Cingular. Currently, Cingular has the largest US footprint (since the merger of AT&T Wireless) and the most roaming partners internationally. Because Cingular has a 30 day return policy, you could also try them and see if your experience improves. They are GSM, like T-Mobile, so if GSM is the issue in your area, then you may not have a better experience. Verizon and Sprint have 15 day return policies, so you can also try them without worry, just for a shorter time.
I think you are going to be able to tell right away. It looks like the clear winner in terms of coverage is Sprint. They have very solid coverage in your entire zip code according to their coverage maps. Verizon would be second best, third is Cingular and a distant fourth (as you are already well aware.is T-Mobile). It appears that this area is better served by the providers who have CDMA technology, versus the GSM ones and that may be because of the terrain.
Also, I just found out that Sprint has gone to a 30 day no risk trial and also has free incoming minutes while you are on the Sprint network. Since your apartment would be on the Sprint network, that might work very well for replacing your landline phone. I might suggest getting a Sprint phone (if you like the Razr, I would stick with that phone since as I had said before, it is a very good phone, but you will need one from Sprint because your T-Mobile Razr is a GSM phone) a month or less before your T-Mobile contract is up so that you can test them side by side.
If you decide to go with Sprint, then just go back and ask them to port your T-Mobile number to your Sprint account and replace the number that they give you.
Victor Epand is an expert agent for BuyCellularPhones.info, a huge cellphone superstore featuring great prices and rebates on cellphones including Motorola, Samsung, Nokia, Audiovox, LG, RIM Blackberry, Sanyo, Sony Ericsson, and others.