What phone should i get, or am i best staying with the one i have.?

I currently have a straight talk phone where i pay close to 50 per month for Unlimited talk/txt/data except the internet/data sucks but it's not really important since i don't really use it. and i just got an EnV Touch from a friend and when i went to go activate it Verizon says the lowest plan where i can have Unlimited txt on it is one where i pay 65 dollars a month not counting tax which i really don't want especially since it cost me cheaper to stick with my current phone and i will basically get the same coverage since Straight Talk works with Verizon or something. Another option is to activate the Touch on Cricket which offer 50 dollars for Unlimited every thing which i think is really good idea since ill have a better phone and be paying the same price for service. But i don't know if cricket has good service. So i'm thinking about getting a totally new phone this summer but i don't know what to choose basically i know its going to be an android smart phone but the provider is what i don't know who to choose. its between AT&T and T Mobil. one thing i would like y'all to consider is that since AT&T bought T Mobil, is going to ,maybe?. how will that affect me in the future and i don't really like to change phones much cause i don't really have much money to spend and when i do i would like it not to be on a new phone so i want to know whats my best most secure move to make. also i would like the service to be prepaid no contracts and really talk doesn't matter just the txt and internet since i txt and internet is an important thing in smart phones so wifi compatible is preferred while, a prepaid data plan is also good