Hotel OYO 321 D'Elegant is fantastic bang for your buck - it's very cheap, and the accomodations are perfect if you don't plan to spend much time in the room (which is quite small, but clean and all you really need as a home-base while touring the city - and the A/C is excellent).
The hotel is in an ideal location, right on Jln Alor St., a popular walking street full of lights, restaurants, and street food. Right around the corner from a street of bars and some nightclubs, but far enough not to hear them from the hotel.
It's also close to the KL Menara Tower, and the Petronas towers.
The staff here are excellent as well, very friendly and generous - the owner fed my friend and I one night, from his kitchen. Best chicken fried rice we've had from Taiwan to Malaysia!!
Just all-around great hospitality! Would definitely stay again if in KL in the future.