Background: Both 1st and 2nd-generation (gen) EGFR-TKIs are recommended in advanced NSCLC with common EGFR mutations. However, there are few data about the difference in the efficacy of EGFR-TKIs according to types of EGFR mutations and agents. Methods: This retrospective real-world study evaluated the outcome and clinicopathologic characteristics including the type of EGFR mutations in 237 advanced NSCLC patients (pts) treated with 1st or 2nd-gen (afatinib) EGFR TKIs as first-line therapy. Results: The median progression-free survival (PFS) and overall-survival (OS) of all pts were 11 months (M) and 25M, respectively. In univariate analysis, pts with exon 19 deletion (del) (n = 130) had significantly longer median OS compared to those with other mutations (L858R: 84, others: 23) (30 vs. 22 M, p = 0.047), without difference in PFS (p = 0.138). Pts treated with afatinib (n = 60) showed significant longer median OS compared to those treated with 1st gen TKIs (gefitinib: 159, erlotinib: 18) (30 vs. 23 M, p = 0.037). In pts with exon 19 del, there was no significant difference in median PFS (p = 0.868) and OS (p = 0.361) between pts treated with afatinib and those with 1st gen TKIs, while significantly better PFS (p = 0.042) and trend in OS (p = 0.069) were observed in pts receiving afatinib in other mutations. Exon 19 del was independently associated with favorable OS (p = 0.028), while age > 70 years (p = 0.017), ECOG performance status ≥2 (p = 0.001), primary metastatic disease (p = 0.007), and synchronous brain metastasis (p = 0.0026) were independent prognostic factors of poor OS. Conclusions: The EGFR exon 19 del was associated with favorable OS in advanced NSCLC pts receiving first-line EGFR TKIs. Moreover, in pts with exon 19 del, first generation TKIs seem to be a reasonable option if osimertinib is unavailable.