OP actually asks a good question, one that is not addressed very well on FT as most of the threads relating to credit cards address limited-duration signup bonuses and not everyday spend.

Clearly there are many signup offers that come and go, but in terms of earning power purely from your average monthly non-travel spend the airline and hotel cards are for the most part very consistent: 1 point or mile per dollar spent. However there are some exceptions:

(1) SPG Amex is often considered one of the best for everyday use as it offers 1.25 miles per dollar when you transfer SPG points to airlines (20k minimum -> 25k miles). On the minus side, Amex is notorious for providing low limits, erratic CS and of course is not accepted everywhere and has a high forex fee when used outside USA.

(2) Chase British Airways visa also provides 1.25 miles per $ but only on BA. However you can use BA miles to fly on BA's parners like AA, and there is no forex fee. You can also earn a 2-for-1 coupon each calendar year by spending $30k. On the minus side, BA has absurd "fuel surcharges" which effectively require a payment of $400-700 for each free ticket, making them useful only for biz/first travel if you are flying USA-London.

Any I missed? Gary had a good column on this at viewfromthewing (see above) but alas the search function is somewhat mediocre.