Dear Samuel Akande ,

I believe this article is interesting, as a comparison of positional accuracy is made between these two raster datasets:

Article Comparison between absolute and relative positional accuracy...

Considering the mapping scale, according to the standards required in Brazil, the DEM SRTM is indicated for scales smaller than 1: 50.000, on the other hand the DEM ASTER is less accurate, being indicated for scales smaller than 1: 000.000.

1. You can use fused DEM (from SRTM & ASTER). It is available as two products: MERIT by yamazaki (uni. Of Tokyo) and EarthEnv DEM90 ( collaborative project of NASA)

2. Choose among TanDEM-X 90m openly accessible DEM from DLR or ALOS PALSAR 12.5m RTC HR DEM dataset depending on application and topography.

3. Try Earthexplorer and other platforms of openly accessible data for some more local option, if available. At places it may be available as: lidar DEM or aerial product.

Best wishes