Folder vs. MBTiles
For output file format in command-line, see the MapTiler manual.
One step before the rendering, it is possible to decide, whether you want to save your maps as Folder or as an MBTiles file.
Folder contains a structure different tiles sorted to directories according to the zoom levels. To load folder on the hosting server takes longer, but the response on the website is then faster.
MBTiles is a single file, that can be easily loaded on any hosting and the upload time is shorter. However, the reponse for the users of your website is a bit slower then for the Folder structures. MBTiles are also suitable for imports of the maps into mobile devices.
Recommendation: If you render smaller maps or maps for your mobile device, use MBTiles. For larger maps and requirements for a fast access from end users, render into Folder and use a stable and fast hosting solution.