Roku doesnt receive OTA, you have to use something like an HD Homerun with Plex or a Tablo. I have several setups. An old DTVPal DVR, Tivo Roamios and a couple of Silicon Dust HD Homeruns that I use with Plex to record and previously used NextPVR with on a computer. The HD Homerun can be used on a Roku via Plex or it can also be used with an Amazon Fire Tv via Plex or there is a native HD Homerun App on the FireTV's for watching Live TV or subscribing to Silicon Dusts dvr service.
In my location, they all are the same in terms of signal reception with a mix of VHF and UHF stations that are mostly in the same direction and about 20-25miles away.
The Tivo is the most user friendly. The Tivo in conjunction with a Tivo Mini allows for multiroom use and doesn't require a computer or external drive somewhere to record.
The HD Homerun is a network tuner that via Plex or the HD Homerun app on the Fire TV also allows for multiroom use, but the dvr functions are not as user friendly as the Tivo.
The Tablo is also a network tuner that can allow for multroom use, but I don't have any working knowledge of it.
ATSC3.0 is a consideration, but you have to buy for now and not worry about 5-10yrs from now. 3.0 most likely will become available in the next year but it wont be widespread. There are no tuners available yet and they wont be cheap when they do appear. For the next couple of years, I would go with a Tivo Roamio OTA if they are on sale anywhere from $299 or lower, just for the standalone convenience and the features of the Tivo software. Also the other options are not as user friendly in the setup and will be daunting for some, which is why I went with Tivo's for my mom and stepmom.