First, let's narrow this down. You have a daughter. SCDSL is very strong with the girls. Just looking at the National Cup finals last year for olders, there was 1 CSL team to make the finals versus 9 SCDSL teams.
Girls 2002/15U Round 2 Slammers FC G2002 Reserve v. Legends FC G02 Academy (SCDSL v. SCDSL)
Girls 2001/16U Round 2 Rebels Soccer Club - G01 Elite v. South Slammers FC G01 (CSL v. SCDSL)
Girls 2000/17U Round 2 Slammers FC G2000 Reserve v. Legends FC G00 Academy (SCDSL v. SCDSL)
Girls 1999/18U Round 2 DMCV Sharks G1999 - Nastic v. LAGSB 1999 Elite (SCDSL v. SCDSL)
Girls 1998-97/19U Beach FC G98 Academy v. Legends FC G98 Academy (SCDSL v. SCDSL)
To say that CSL Gold is the equivalent to SCDSL Flight 1 Europa is probably accurate, but the highest level of CSL is Premiere and that is the equivalent to SCDSL Flight 1 - Champions bracket.
SCDSL dominated the girls side in the California Regional League as well (2016 Girls Champions = 6 SCDSL and 1 CSL (Rebels). With the DA, maybe some things have changed, but if I had a girl, the SCDSL is the league to be in (assuming she is not playing for a Girls USSDA team or an ECNL team).
On the boys side, CSL tends to dominate over the SCDSL. So far, Boys Champions in 2017-18 (younger = all TFA / CSL) compared to Girls Champions (all SCDSL).