I'm working on a GPS track visualizer for quite some time. It shines in hilly and mountaineous terrain (where a 3D view makes more sense), but it also offers quite a lot of Strava-like features (statistics etc.).

You can upload your GPX and FIT files manually, or sync directly with Garmin, Coros and Polar.

See https://cubetrek.com for the live app and check out some examples there. It's free and opens source.

Also, anyone who likes to work with 3D visualizations (especially Babylon.js), let me know if you like to help polish this thing further.