I can't understand why anyone would rather face Philly than Chicago right now. Chicago is a shell of a team and Philly (as you said) has been a horrible matchup for the C's this year. I'd be very much worried they'd run the C's out of the gym. Of course as some have said..if the Celts are hitting their shots then Philly will have to play halfcourt which swings things back in the Celts favor.
But still..if you're looking at the two teams straight up right now? Bulls are the easier team to beat. They played all year with the idea that Rose would be back at some point..now that it's clear he won't be they seem to have lost some of their heart/will (along with Noah be hurt of course).
Well, I'd much rather have home court advantage against a young team with little playoff experience than no home court vs. an experienced, albeit depleted, Bulls team.