How well OTA TV will serve your needs depends on where you live and which programs you watch. You won't have access to cable-exclusive programs anymore, unless they happen to be available on the network's website (which seems to be becoming more common). It would help for us to know your location, since we can't tell how many channels you'll receive without knowing which market you're in.
As for a DVR, keep in mind that most OTA DVRs don't work the same way as cable ones do. They don't make name-based recordings and find your programs for you: you either click on the guide to set a timer to record that timeslot, or you set up a manual timer, the way you would with a VCR. You'll record whatever is broadcast during that timeslot, so if your program gets moved at the last minute, you'll miss it. OTA guide data is also determined on a station-by-station basis, so how much program information you see and how complete it is will vary by network. The main DVR options still available are:
Of these, only the CM 7400 and TiVo support paid guides that will let you continue to do name-based recording, but current TiVos no longer have OTA tuners, so you can't use the latest model with an antenna.
The other models have their own quirks and bugs, some worse than others. It would help us to make recommendations if we knew some of your priorities.