For me it's the opposite. I too read Umineko first and then Higurashi, but I still think Umineko is best. The soundtrack, the plot, the rytmh of the narrative, I think it's all an improvement from HigurashiI started with Higurashi, but bounced during the first hour due to SoL stuff.
Read Umineko then, and thought nothing could beat it.
Then I read Higurashi last year and... yea, it's better than Umineko. Has that 'debut punk band album' energy, while Umineko is like a 'progressive rock studio album'.