You may also want to consider pricing implications of both. Desktop software can usually be sold for a higher up front cost, but it's tough sell to make it subscription based. SaaS would make your life a lot easier if you have a webapp. People are starting to get used to paying monthly for a service anyway.
Pro tip: If you decide to make a native app, don't use Electron. Instead, use the built-in WebBrowser/WKWebView components included in .NET and macOS. Create the UI once using whatever web framework you want, and code the main app logic in C#/Swift. Although the WebBrowser control kind of sucks right now, Microsoft is planning on releasing WebBrowser2 which will use Blink. I think they might also have it where the libraries are shared between all apps using it, to further reduce bloat. The old WebBrowser component can be configured to use the latest Edge rendering though by adding in some registry keys or adding this meta tag:
<meta http-equiv="x-ua-compatible" content="ie=edge">