I am working on TCGA lung cancer data , I want to compare Average expression of a set of gene (my interested set of gene) in normal and tumor samples. I am wondering that the average expression of these gene in normal and tumor samples are very simialr in normalized log2 data , Fig1, (LUAD.uncv2.mRNAseq_RSEM_normalized_log2.txt), but it is different in normalized Z_score data, Fig2, (LUAD.uncv2.mRNAseq_RSEM_Z_Score.txt).
Fig 1, when using (LUAD.uncv2.mRNAseq_RSEM_normalized_log2.txt) data
Fig 2, when using (LUAD.uncv2.mRNAseq_RSEM_Z_Score.txt) data
PS: x-axis, same order of genes
So, please help me, which input data should be approprite for this type of comparision.