Sunrise usually happens in the East (direction of Changi) whereas sunset happens in opposite direction (towards Tuas). There is a seasonal change to that: during midyear the location drifts towards North and end of the year (Dec/Jan) it's more to the South). So same spot gives a different sunrise / sunrise through the year.
Suggest you to try looking for scenes (there are some in landscape section and you can always go onto flickr or 500px) that you like then go to Suncalc or The Photographer's Ephemeris to verify whether it is sunrise or sunset. Then shoot! Good luck.
Reason? The same spot that sun rise today is not going to be the same spot next week and the same spot that sun set today is not going to be the same spot the following week. So there will never be a best location.
So no point getting advice finding the best location. However you can get that sunrise/sunset picture that you want if you do the following:
1. Check the street directory/OneMap/Google Map for suitable location that you can find interesting vintage point where you can take that picture. eg. Relatively Tall Building with Open Air Carpark overlooking the west for sunset.
2. Check which direction the sun is going to set or rise and at what time it is going to happen
3. Check weather forecast whether it is going to be cloudy, thunderstorm or sunny
4. Check what are the mode of transportation and timing that allows you to get there (If you dun drive)
5. Check you bring all the things that you need to get the picture.
6. Check your alarm clock is set and lastly be punctual. The sunrise/sunset are professional people and one thing that they hate are latecomers. They may also fly you kite and dun appear at all. And there is nothing that you can do about it.
As you can see, it takes a lot of time & effort to plan but it only takes seconds to make your exposure (You might not even have a chance if the sun decides not to see you). So forget about getting the advice where is the best location cos the location can be anywhere as long as you are there & prepared to make the exposure. And you can going back to the same spot over and over again until you get that perfect sunrise/sunset picture that you want. How perseverance are you to get that perfect sunrise/sunset picture that you are looking for?
Also, don't just think that sunrise/sunset are the only good times to take photos. Golden and blue hour are also very nice. Blue hour at night is very good for cityscapes because the blue sky contrasts nicely with yellow lights.
Sunrise/sunset can be very nice, but a lot of cameras have trouble with dynamic range if you have the sun in your shot. If you don't, might as well shoot at golden hour anyway.