Suggestions.
1. Like Mike said, Over The Air (OTA), it's free and many HD channels.
2. Pluto TV - Free with some national feeds
https://www.rokuguide.com/channels/pluto-tv3. Amazon Prime Member? You get "Amazon Prime Video" as part of your subscription. Lots of Amazon movies, and Original Series content such as Orange is the New Black and Mozart in the Jungle. Blockbuster Movies, Mockingjay, and so on.
Now comes the part where your specific interests in video entertainment play a part.
4. Sling TV - various package of cable channels, see their site for specifics
https://www.sling.com/#channels5. Hulu - lots of rebroadcast of TV Series, some Hulu series, some Movies - I think they are owned by NBC.
6. Netflix - lots of Original NetFlix contents - They have two different streaming packages - upto 2 people, upto 4 people with 4K content.
7. Tons of other streaming services
You need to consider what streaming device you are going to use.
1. A Smart TV? Will have their own Streaming OS or a Google OS. They typically have a more limited set of streaming apps.
2. Tivo DVR - you can record OTA or you can get one that is compatible with your Cable company if you go that route.
3. Apple TV - I don't know much about them
4. Fire TV - Amazon products, I don't know what they stream outside of Amazon Prime
5. Roku - my Roku came preloaded with around 100 different streaming apps and there are more. Link to ROKU apps available.
https://channelstore.roku.com/browseThe Roku Streaming sticks (new ones) are amazingly capable.
Best of luck on your dive into the streaming world.
Simon