Router for Fractional T3

Hope someone could point me in the right direction on purchasing the
right router.
We are upgrading to a Fractional T3 line (12Mbps). We have about 50
site offices
that currently connect to the main office with SOHO/VPN routers. What
are my
cost effective options?

Cisco 7145 was recommended but its end of life
Cisco 3845 was also recommended but expensive

I am new to the cisco world and hopefull ..
Telecom, Cabling and VoIP continues...
Tags: telecom cabling Networking Internet cat6 fiber optic