Comments from individual members in this forum are subjective, as in most other forums in the internet.
Hong Kong Island is my preferred part for tourists.
If you only have a couple of days, Tsim Sha Tsui is the best area in my opinion. With a couple more days, you might want to stay somewhere that you can find more breathing space (less people) so HK Island would be the preferred side then.
Keep in mind HK is very compact, so staying anywhere between Causeway Bay to Mong Kok typically means you are close enough to the sights and sounds.
It depends on what atmosphere you like (and your budget).
If you wants tranquility, You'll need somewhere more far away from the city.
From the viewpoint of a tourist, I like the Island more since it's more "stylish" (can't think of a better word).
Everyone has their own opinion on this. But, if you stay in Kowloon, the Tsim Sha Tsui part of Kowloon is probably the area of Kowloon that most tourists seem to prefer (though even this is up to your individual preference as well, but as a first time visitor, you should find Tsim Sha Tsui to be among the more convenient neighborhoods to stay in). Many of the Kowloon tourist attractions are located in this neighborhood. It is located at the southern tip of Kowloon, bordered on the south by Victoria Bay. Many people also like to stay in neighborhoods a bit further up the road in Kowloon (a bit more north) such as the Mongkok neighborhood, which many people would feel has a more "local" feeling - that is, less tourists compared to Tsim Sha Tsui and more local people and street life (night markets, etc.)
If you stay on Hong Kong Island, I would recommend staying in Causeway Bay neighborhood or the neighborhood called Central. The Wanchai neighborhood would be my third choice - and only slightly less recommended due to the fact that there is a few block radius of "bars" there, some of which are on the "raunchier" side of things and may not be an environment you want to have to walk by every day (but then again, maybe that is exactly what you like - I don't know).
But, regardless of whether you stay in Kowloon or Hong Kong Island - and regardless of neighborhood - as long as you are relatively near an MTR station (Hong Kong subway) or tram station, then you are fine because the Hong Kong public transportation system is very quick and efficient and will take you anywhere you need to go. The bus system is also very good, but I think it is usually harder for the first time visitor to navigate the bus system.
I think it really depends on what u plan to do while in town. If u r into a local shopping experience, there is no better place than TST. If u want a high end shopping experience, then being in HK Island is the better choice.
Both sides offer enough activities to do for tourists and are good bases to sight see as the MTR and buses are very easily accessible.
I am more inclined towards HK Island only coz I know it better, having lived there for quite a number of years. It is smaller (landwise) and easier to get around.
And again depending on your time in town, for a few days, I do suggest HK island as the main activities always include a trip to Victoria Peak or/and Stanley Market. HK park is there, Sheung Wan, Causeway Bay, etc
HK island is the financial hub so once night falls, Central is a very quiet place, only certain neighborhoods come alive at night (wanchai, causeway bay, etc) so if u stay in Admiralty (immediate neighbor of Wanchai) or Central or Shueng Wan, u can say it is going to be a lot quieter than anywhere in TST which comes alive at night due to night markets, late night dining and shopping.
Since I am not sure what u r looking for in a hotel or what u plan to do in town, I cant recommend a specific area but in general, for a tourist, Causeway Bay is great for shopping and dining as well as convenience (MTR). It gives u a good insight to HK lifestyle from day till night. It offers quite a few choices for hotels for different budget.