I don't know which part of Patchogue you live in. I have a friend who lives over by Carvel on 112, and when I visit him I haven't noticed any service problems. I live in Rocky Point, and I didn't get service from Verizon when we moved in. I'm sure that's different now, just like I'm sure T-Mobile has better service than they did 10 years ago.
I know that T-mobile put up a tower not to far from my home 2 summers ago, and that they had other towers planned for Long Island. (A friend of a friend works for a contractor who recently was hired by T-Mobile to do the installations. He said they spent millions on new towers.) I never had any complaints about their service before, except when I go further out east, but I had those same issues with my short time with AT&T too.
My wife and I recently bought Iphones, leaving behind our Samsung phones. We regret the choice, but had no real option. (long story about that) But we did notice a call and data quality change once we were using the Iphone. The call quality and data is not as good. We sounded clearer on the Samsung phones and data seemed to be a little faster too. I also experience more dropped calls in areas that I never experienced this before. I blame Apple and their proprietary software for most of the problems. But it is important to note. I don't know if other carriers have similar issues with the Iphone, but it adds to the list of reasons why I HATE the Iphone.
The only thing I can really say is give T-Mobile a try. You have a 2 week window where you can return your device and cancel your service with no penalties. (I think there is a restock fee) But if thats true, its still better than getting locked into paying for a phone for 2 years.
But my wife WILL NOT LET ME LEAVE T-MOBILE!!! I talked about it about 1 year ago, but my wife is dead set on never, NEVER going back to Verizon or AT&T. For billing reasons, customer service reasons, and all in all satisfaction.