Siem Reap is a tourist town, so you have a wide range of accommodation choices, ranging from cheap hostels to luxury 5-star resorts. The quality is excellent, and the prices are low if you come during the low season and are flexible enough to book on a last-minute basis. I mostly stayed in the Tara Angkor hotel (which I highly recommend), before renting an apartment on a monthly basis in the "Steung Siem Reap" residence.