>Is a 1084 better than a Microvitech M1438s?
No. The 1084 is a basic video monitor which only accepts 15kHz modes (from the standard amiga chipset). It's been around since the beginning of the Amiga, almost, and in many different variations.
The M1438 is a multisync which can handle both Amiga native chipset modes and higher frequency rates, and so is much more useful.