I'll be spending most of my holiday in the Philippines however I want to venture out to. Should I go to Singapore or Malaysia??? Is 3 days or 4 days enough?
Singapore or Malaysia
Go to Singapore - you'll be able to see most of what you want to see in about 3-4 days - Malaysia deserves/requires a longer break.
Depends on what you are interested. Singapore compared to other cities in Asia is extremely modern and busy with all the traffic. If you like big organised cities with a lot of shopping malls then you should really go to Singapore. You will be also able to explore the chinese, the indian and malay part of the city. But I was disappointed of Singapore because it seemed to me too westernized.
Instead I really like KL. Still a typical asian city and a lot of food stalls outside. The atmosphere of the city is very fascinating and the whole life much cheaper than in Singapore. If you have enough time, why don't you fly to one of the islands on the eastern coast for the beautiful beaches...
I'd say go to Singapore after the Philippines... Singapore has a lot to offer and their tourist spots are just within 30mins apart. Singapore is a small state and you can see most of it within 3 days alone.. you just need to organize itinerary to make most of your stay there...
they've got Sentosa, the Night Safari, the Jurong Bird Park.. it is indeed very westernized specially if you stayed most within Raffles area... but you may experience the Chinese culture in Chinatown.. immerse into Indian culture in Little India... the people of Singapore is composed of Indians, Chinese and Malay.
Compared to KL, Singapore offers better mode of transport and so you can easily reach your destinations using the bus and MRT systems...
3-4days (maybe you cant cover whole Malaysia but you can cover KL)....I would say KL....Almost as same as Singapore but KL is much cheaper. You can get almost every kind of food here. The original Malay food and Mamak's food here is much better compared to Singapore's. Twin Towers, KL Tower, Eye On Malaysia, Bukit Bintang, Chinatown, Arabic Town(near Bkt Bintang), Alor Road(for local chinese food),Batu Caves, Central Market(local souvenirs), Putra Jaya etc.
Public Transports are efficient enough. You can travel by local bus with a day ticket or by the LRT and Monorail. Just make sure the taxi drivers use their meters.
Adysli is absolutely right, go to Malaysia -KL 
Opospa is right too 