Choice of individual boxes might have as much to do to comparison of CAPEX/OPEX costs as how you plan to use them today and over the next couple of years.
Big boxes, often big $, but might provide you options not available with smaller boxes. For instance, how critical loss of one indivdual box vs. redundant box with spare PA on hand?
As to 7201s in particular, for individual DS3s, 3825 or even 2851 might be good enough.
Within the 7200 series, perhaps two 7206VXRs or three 7204VXRs, with G2s, might be less expensive and provide the option of having all DS3 links active if a single router fails. Depending on your routing topology, individual routers vs. multiple link routers could impact load balancing.
If avoiding single router single component failure important, before jumping into the larger chassis routers, you might also consider a two or three 7304 routers.
