The Elagato devices use either Empia 28xx or Conexant CX231xx series of chips to power their devices. EZcap uses Empia 28xx . Both chip sets - and thus the related devices - have similar specs....
The software supplied with these units can vary in ease of use and quality, and usually involves real time encoding to a compressed format like Mpg2 or H.264.
In either case you're probably better off using alternative (free) software and capturing to a less processing intensive intraframe format, and modifying the results with editing software.
Blackmagic make fine quality devices, but are not usually well regarded in their ability to capture older SD formats very well.
DaVinci Resolve is top quality free editing software, but needs a beast of a computer to work well - and does have quite a steep 'learning curve' at the start.
Everyone has their own favourites of course, and we do all tend to think - naturally enough - that our own choices are the best
What is perhaps unusual is that - unlike most things in this life - some of the very best video editing software is actually free!