Virginia Bakery in Berkeley perhaps? Love their cakes. They've been there at least as long as I've lived in the Bay Area and I've been here 17 years.
Or maybe Neldam's (though I've never tried them) which has received a lot of praise here. They've been there forever.
Neldam's Danish Bakery
3401 Telegraph Ave, Oakland, CA 94609
1690 Shattuck Ave, Berkeley, CA 94709
The best homestyle cake anywhere is this little place in San Leandro:
Marita Sweet Potato(e) Pie Co.
600 Dutton Avenue
(although the place is right on Bancroft Ave. across from Safeway, go figure)
The cakes are like the ones Mom makes. Dense, rich, layers topped with creamy butter frostings, not always perfectly proportionate (you know, the cake sometimes leans a bit) but oh my gosh, excellent! They are famous for their red velvet cake with or without pecans. I have tried the coconut, 7-Up and chocolate cakes, all worthwhile. They also make cupcakes, turnovers, fruit and meat pies. The prices cannot be beat. Cakes are sold in slices, halves and whole. A whole cake costs between $13-15. The couple who run the place and do all the baking are nice people. I have been known to buy one of these cakes for a family function, take it out of the box, place it on my own cakeplate and have everyone at the party request the recipe. Highly recommended.
There have been recent favorable posts about Crixa Cakes in Berkeley (Adeline at Carleton), where they sell their cake by the slice. I've linked Stanley Stephan's below, and he/she's got a link in his/her post, too.
You can also search from the main Chowhound page for "Crixa" and find more opinions.