That is a really wide question and the answer depends very much on your personal preferences, budgets, etc. There are generally three types of accommodation options in Niseko:
- Holiday apartments
The vast majority of people stay in apartments or chalets, as the choice of hotels is fairly limited (including the Hilton and Greenleaf hotels in Niseko Village, Prince and Alpen hotels in Hirafu, and a few smaller hotels). Most of the hotels are good but not luxury. Some of them also offer ski-in/ski-out (or something to close to it). They can be a bit pricey, though.
Holiday apartments are located primarily in Hirafu, but there are also some in the other villages. Many of these have been built in the last 5 or so years, so tend to be more modern and comfortable than the hotels (some really swanky/luxury). Depending on location you can get close to a ski-in/ski-out experience (esp. if in Upper Hirafu), otherwise it is generally a short hike to the lifts or to a shuttle bus stop (but if you are in lower Hirafu you could be looking at a 10-15 minute uphill slog through the snow). Most of the holiday apartments are privately owned and managed by operators like Hokkaido Tracks. Prices vary widely depending on locations and level of luxury.
Lodges/chalets have the most variety, so it is a little difficult to generalize. They can be individual houses put up for rent or could be groups of houses operated by a management company (similar to the way holiday apartments work - Country Resort outside of Hirafu is an example). The latter are typically quite new and western-style (again, similar to the holiday apartments), while for individual houses it can vary a lot (from little shacks to big mansions and everything in between). Locations also range from right in the middle of one of the villages to somewhere more isolated - if not centrally located there is generally a bus or shuttle stop within walking distance (some of the bigger clusters operate their own shuttle). This category has the best bargains and even the higher-priced (and very nice) houses tend to be considerably cheaper than options 1. and 2., but depending on location might require a bit more effort to get to the slopes and for things like eating out, grocery shopping, etc.
Is this your first time to Niseko? Also, when will you be going - the season is not quite over yet, but it is definitely 'spring boarding' now and the season will draw to a close soon.