I looked through lots of digital signage player (free of charge and prepaid). Compared to Xibo 90% of them have less features in terms of visual effects.
I recommend you to consider Adobe After effects. There you can prepare nice transition effects. Currently I am doing fade in fade out there.
Also consider teaming After Effects with PowerPoint. Prepare video in powerpoint and do post processing in After Effects.
The main problem here is a lag between transition from end of the video to the start of the next video. So, using fast hardware will help here.