VMs mapping requirements are currently very simple. Literally, in the projection sense.

Tile rendering
Common interactions
Compositing of additional elements

While the metaphor is a map, this doesn't mean a javascript GIS library has to be used. This is a quick go over options.

Leaflet

https://leafletjs.com/

What is currently used, and have most experience of in the team. Very widely used, lots of plugins, familiar to users, and stable. Also a little dead, core people went off to do mapbox, and most active development is in plugins rather than the core tool.

Normal operation uses svg elements in the dom and css transformations, which is nice and introspectable and extensible. Has a few gotchas with z-order, and performance implications for large numbers of items, which require aggregating before insertion. Being an old library, expects to control its own page content and state directly, and interfaces through dom events. This makes working in the react model a little awkward, but reasonably managed by react-leaflet library, or similar approaches.

Mapbox

https://www.mapbox.com/

Vector tile centered mapping, using webgl, though has raster tile support. Doesn't support multiple coordinate systems, can't find examples of people using it for non-geographic maps. Overall experience on examples is good, however though the documentation is extensive it's not very clear how to actually implement common functionality. Basic operation requires an api key, where the freemium wall lies is also not clear. Possible barriers to offline deployment?

They have released quite a bit of code, but in recent years it is not well maintained, priorities perhaps switched to internal/commercial concerns.

OpenLayers

https://openlayers.org/

Active development, though documentation is spotty feeling, has dead links, overall confusing. Code quality looks broadly okay though. Core component composites to canvas, so a little more opaque than leaflet, but api level is broadly similar. There's some integration with mapbox's vector approach and style specification.

The updating of tiles on zoom feels wrong to me. This may be psychovisual as it lacks a crossfade, it may actually be something slower in animation/network fetch/execution.

OpenSeadragon

https://openseadragon.github.io/

Not a mapping library, but does tiles and deepzoom. Can be used to make very smooth feeling interactions, though the defaults are actually somewhat awkward. Supports overlays and user interactions, and plugins for much more (particularly annotations). There's not much in the ecosystem that's related to orientation/navigation or editability, generally assumed from position in image, and optional minimap.

ThreeJS

https://threejs.org/

Thin wrapper around WebGL. Mentioned mostly as the far extreme. Possible to implement smooth tile transitions with custom shaders, ray casting hit detection, all kinds of fancy dynamic effects. Considerable work to do so however.