The Swpier display widget provides a selection of transition animations, easily switched through the block edit dialog. Here we have the usual set of images displayed using each animation in trun. So as not to distract, no slide information is overlaid and the lightbox link is switched off.
Slide is a good choice for showing a single image at a time and for carousels showing multiple images at a time.
For comparison, here is the same slide effect in a carousel showing 3 images at a time. This transition looks good for any number of images. In the display widget you can set breakpoints to display different numbers of images depending on page width.
Fade is limited to one slide showing at a time. WIthin fade, an additional option is available to cross-fade.
Cube is also limited to one slide showing at a time. Within cube, additional options are available to control shadows beneath images and the overall cube.
Coverflow looks good for single images at a time or 3 images at a time. It will also look ok for 2 images when the center option is used.
Coverflow will render to show 4 or more images at a time, but the overall effect becomes ugly.
The maximum sensible coverflow is a strip of 3 images. With the default coverflow options, any more slides and it gets weird. Further options within coverflow can be used to create some unusual effects that work with more images visible.
Flip is another animation limited to one slide showing at a time. Within flip, additional options are available to control shadows and edges.
The cards animation was introduced with Omni Gallery 1.9.0. It shows slides as a hand of cards with an animated shuffle to swap. The animated changes look best when using drag/drop, so are particularly effective for touch devices.