The two are practically interchangeable, and over time, maintenance is the big issue. There is usually a price difference. If the nickel is worth it to you, why not? Be aware that due to its slightly yellower tone over the polished chrome, it may be slightly more difficult to match, as different manufacturers have slightly different colors of nickel. In both cases, be sure that the finish is over brass, for added toughness.

Buy a sample knob or handle in chrome and one in nickel. Pour some reasonable acids (lemon juice, cider vinegar) on each, let them sit a few hours. Try cleaning with normal household cleaners. Scrub with SOS pads, nylon scrubbers, whatever you would usually use in cleaning. With new things, you can usually avoid Ajax and other highly abrasive cleaners that will wear off the finish. Chrome plating is a much harder finish than nickel. Both should be over brass, as sooz001 says. Avoid plated pot metal and plastic.