Make a list of your must-have channels, and pick the cheapest solution that has them.
Are you sure your Roamio can’t get OTA (the 4 tuner can, the 6 tuner Pro can’t)?
Since you can’t get cable, does that mean you can’t get internet either?
In any case, TiVo and DirecTV DVRs are functionally very similar. Both have a guide, can record things and play live TV, the basic things you’d expect a DVR to do.
A basic DirecTV package with DVR is going to be around $120/month after promos expire, close to $200 for the top package. OTA is free. Streaming is anywhere from $20/month to about $160 on top of your internet service cost.
I would try to cut the cord and do OTA only. If you can’t stand it, switch to satellite or streaming later.