Your taste will influence choice but there are some things to consider.
There is a certain style associated with a wetroom floor, the uninterrupted floor expanse can enhance the perceived size of the room and creates a beautiful aesthetic by avoiding the colour and texture change of a showertray. The general feel and ambience is clean and modern, with no step up into the shower area, but there are reasonable arguments for either style.
Cost.
Have no doubt, a wet floor system will cost you considerably more than a showertray! All told, in a typically sized modern bathroom, the difference in cost could be in excess of £1000 GBP, and possibly more in a larger bathroom.
Additional cost comes with the materials and also with the labour for installation. The waste system is different and the drainage requirements are more critical on a wet floor. Naturally water needs to drain away downhill, so with the entry point to the drain being lower than with a tray this requirement can provide a challange.
