Unless you just enjoy the experience of using a router, go for the table saw. If you are using 1by 4's you can do the measurement from the edge of the board and just flip the board around and run it through again. Using a piece of scrap set the blade 1&1/8" from the guide and run it through both ways. If not correct you can make the correction. Nothing easier than that. Same applies if the boards are wider, just different measurements.
Depth, doesn't really make much difference. 1/4" too much, 1/8" not enough.
