Would it be a good complement to tell my girlfriend that she reminds me of Sofia Vergara?

No … tell her that Sofia Vergara reminds you of her …

No. Don’t compare her with anyone

hasn't sofia been divorced/separated multiple times?

No, don't tell her she "reminds you," tell her she "looks like" Sophia Vergara.

Not gonna lie, that actually works. Many years ago, I told a girl she looked like Jennifer Anniston, needless to say, "the rest is history." 😎

It's not bad 🙂

Just tell her she is beautiful and don't compare her to anyone.

Make sure you pronounce it Sofia Vi-agra