In order to identify the good GGM that can provide reliable deflections of vertical data, you need to make self evaluation on the model. Each global gravity model have their own characteristics depending on our location. It cannot simple said that which model is good.

The EGM2008 with Deflections of the Vertical (DOV) found at http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm2008/anomalies_dov.html

What you can do is to inter-compare gravity induced DOV from different models and judge upon their level of inter-agreement.

Generally i am not very sure to say which model is the best one for vertical deflection, but basically based on my experiences, EGM 2008, up to degree and order 2190, can provide reliable data for vertical deflection, i just say it about the filed that i evaluated these provided data.

Ismael,

Honestly, you have to evaluate each GGM as they are built using various normalization, stabilization, and local/global optimization techniques which make their performance vary depending on the scale of the problem, i.e. local, regional, or global.

In some cases, the EGM2018 was found to be the best model, where in the Red Sea, the GOCO-based combined models outperformed it.