You can definitely get better rewards overall if you are willing to carry around a stack of credit cards and shuffle through them every time you make a purchase. I only carry my driver's license and one credit card most of the time.
For me, CSP gives the best rewards of any single card, but no single card can match he rewards of a gaggle of cards.
You can get pretty far with NAF cards:
5% Dining - Citi Forward
3% Groceries - BCE
3% Gas - BankAmericard Cash Rewards
2% Travel - BCE
But I still value CSP for its incredible flexibility and customer service. Who knows? Maybe I'll be singing a different tune next time my CSP annual fee comes due.
But don't forget that the Chase Freedom rotating categories are effectively 10% or so when transferred through CSP to miles program.
This, of course, assumes you travel. I do. It's one of my top spend categories. YMMV