So any decent speaker should satisfy your desired frequency response. Impedance is the measure of the resistance that a speaker puts on an amplifier. So you have to be very careful to match the speaker to amplifier impedance. 8 ohms is the standard, but most receivers are built to withstand impedance loads much lower than that. Don't pay much heed to other parameters such as timbre matching and decibel sensitivity.
All manufacturers design their speaker to sound tonally the same.
Interconnects and speaker wires can enhance or hinder the system performance. An easy way to pick these accessories is by price and quality. I would recommend Kimber Kable, Straight Wire, Monster, XLO, Esoteric, Liberty Wire, MIT, Nordost, and Synergistic Research. If you think buying a pair of speakers is mind-boggling enough, it's not over yet. You now have to position it to get the best out of it.