I like 5 as it curls around downtown and the jets roar overhead on approach to Lindbergh Field.
The 163 is lovely, particularly where it crosses Balboa Park. Especially at night.
15's bridge through Mission Valley and then up the hill appeal to me. The newest section with the underground sections are neat, and I like the southern end even though it drops me off at work.
I even like the wannabee freeway section where 125 and 52 join up.
The 805 is functional, industrial, full of purpose. But I have no love in my heart for the 805.