Is it permissible to say: "O Allah, accept from us our righteous deeds," while believing that Allah is Good and accepts only what is good, or is it more correct to say, "O Allah, accept from us our deeds"?

There is no harm in supplicating with the words: "O Allah, accept from us righteous deeds," because Allah accepts righteous deeds and does not accept evil ones, as stated in the Holy Quran: (Those are the ones from whom We will accept the best of what they did). The word "righteous" in the supplication is an explanatory adjective revealing the reason for acceptance, and it is not a condition to exclude unrighteous deeds from acceptance. This is a valid linguistic style. Scholars have used this supplication, among them Sheikh Ibn 'Uthaymeen, may Allah have mercy on him.