The island of Flores is so small that any place to stay on the island will probably do. That being said you may want to shop around for a place or a room with a view that you prefer. I stayed 4 nights at Hotel Casa Del Lacandon. The rooms were definitely cramped and the beds were not the most comfortable, but the price was right. I shared a small room with two single beds and private bathroom for less than $7 each. I also stayed in another cramped room for two nights on my own for $9 per night. A few of the rooms in the rear had great views of the lake. If you didn’t have a room with a view you were only steps away from a magnificent view from the terrace.
The showers had plenty of hot water and the wifi was reliable. These two things, along with the spectacular terrace view make Hotel Casa Del Lacandon a nice budget option for backpackers. The owners are nice and also speak a little English. They offer laundry service and meals at the terrace cafe. I needed a place to store my computer the day I visited Tikal and the owner kept it locked up in his room. Not an ideal place in my mind, but it was my best option at the time and it worked out well in the end.