These aren't bad, for not much more then the cheaper AV2HDMI converters. You get the addition of S-video, and they don't just do 1080p.

https://www.amazon.com/gp/product/B00V2ULHBS/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

As far as the picture being strecthed to 16x9 can you change that on your TV?

Doesn't Rca to HDMI, component to HDMI, scart to HDMI and s-video to HDMI make the quality of the video garbage?

Depends on the upscaler. Some are bad. But you can find some good $50 options. I had good results with this one in my testing months ago: https://www.amazon.com/Tendak-Composite-S-Video-Converter-Upscaler/dp/B00V2ULHBS

Though I only tested with an N64 which has a rather smudgy signal anyways.