I just wonder what the advantages of using/bying a GW121 meter is.
It's blue.
Because of a lot of silly posts like this, it can be hard to find information on the forums.
Counterpoint: it's as good an answer as anything else to such a general and open ended question. I could give a 2 page comparison of features, ranges, and performance of a handful of comparable meters. It would take me 45 minutes to write and would help nobody because if they cared they would have read the spec sheets and manuals to find the information themselves.
A question about specific features, first hand experiences and opinions, or anything more concrete would invite more helpful answers.