If you get a Firestick make sure it's 4k capable, as a new TV will most likely be 4k. The devices under $50 are usually 1080p.
Amazon Fire TV with 4K Ultra HD and Alexa Voice Remote - Streaming Media Player
The Firestick works with Alexa voice commands from your remote, Echo or Dot.
Remember, the picture quality will mostly depend on the TV you chose and there are many good choices.
I prefer the streaming sticks/devices as they have an extraordinary amount of apps as compared to smart TVs. I also have Smart TVs and Smart Blueray players and have found they aren't as fast as the streaming sticks and are slow to update and add new apps.
The price difference between a Smart TV and a TV + streaming device is negligible these days.
YMMV, good luck.