Some people might say that I'm an authority on commuting between Singapore and Kuala Lumpur . I would have to agree with them. I've gone through the causeway, pass Ayer Keroh and the other way around so many times that I'm able to pinpoint where I am by looking out the window. The trees and hills become familiar and even the curves of the roads are imprinted in my mind. Yes, that takes a whole lot of years of practice, many bus rides and thousands of dollars. I would even go as far as to say that I've probably tried every mode of transportation (barring the seafaring kind) and every combination humanly possible to get home. The most common and convenient being the express bus. There are many different express bus companies offering transportation to and from Kuala Lumpur and Singapore . It's affordable and not as time consuming as many might think. Here are some of my personal favourites.

First Coach @ Bangsar (KL)/ Novena Square (SG)
This friendly and convenient express bus service tops the list because of its departure and arrival location. Not many bus services come with the convenience of a LRT/MRT station within walking distance. If you're in KL, First Coach buses depart from Bangsar and Novena Square if you're travelling from Singapore . It's all within walking distance to the Bangsar and Novena train stations. The buses are very punctual and it's a non stop journey, with a 10-20 minute toilet break in between. The only setback with First Coach is its no frills policy. They do not serve food on the bus but a bottle of mineral water will keep you company throughout the journey. Biscuits and crackers are distributed before the bus departs but that's about all the food you're going to get from First Coach. This is turns justifies the reasonable prices:

Purchased tickets in KL:
KL -> Singapore: RM40           Singapore -> KL: RM60

Purchased tickets in Singapore :
Singapore -> KL: S$30            KL -> Singapore -> S$20

First Coach is highly recommended if you are looking for a simple express bus with no frills. Movies are shown occasionally so it really depends on your luck. The air conditioning might get pretty cold so it would be advisable to bring a jacket or a small blanket aboard. This would be considered one of the newer express bus services as it is roughly 2 years old but its popularity has grown immensely. Getting tickets last minute is somewhat of an impossible feat so be sure to book your tickets in advance.

Nice Express Bus @ KTM Station (KL)/Copthorne Orchid (SG)
This would undoubtedly be one of the most luxurious buses that you can find. Comfort and convenience is what they're trying to achieve and I must say that they've succeeded. There are 2 variants of buses for you to choose from, Nice 2 and Nice ++. Nice 2 is a double decker bus where else Nice ++ is a luxurious 18 seater bus. Both services get you where you want to go but in different styles. The double decker bus (Nice 2) has a seating capacity of 27 and is the cheaper option but not by much. It uses slightly older buses but are equally as reliable as their newer counterparts. The Nice ++ is the latest in super luxury buses. It boasts a personal TV for each passenger and has something like 4 to 5 movies for viewing during the journey. The seats are spacious and comfortable and there's a lot of leg room to move around. Both the Nice++ and the Nice 2 comes with food and refreshments. The most common item on the menu would be a sandwich but sometimes you might be surprised with a hot dog. Either way, the food can only be described as similar to airplane food (if you know what I mean). I highly recommend paying the extra RM8 for the Nice++ because it's a smooth and comfortable journey all the way.

Nice ++
KL -> Singapore: RM80           Singapore -> KL: RM80
Singapore -> KL: S$55            KL -> Singapore : S$55

Nice 2
KL -> Singapore: RM73           Singapore -> KL: RM73
Singapore -> KL: S$49            KL -> Singapore : S$49

Transnasional @ Jalan Duta or Pudu (KL)/ Lavender Street (SG)
Transnasional probably has the most options to choose from. They have a luxury bus that departs from Jalan Duta and the budget buses that depart from the Pudu Terminal. The Singapore arrival and departure terminal is located at Lavender Street , the Melaka – Johor bus terminal as it is commonly known to the locals. Ticket prices range from RM35 to RM80 and S$35 to S$47. The downside of taking the economy coach is the 30 minute break. It is mandatory for the economy coach to make a stop at a designated area for food. This would extend the journey by about 30 minutes. Not such a bad thing if you're actually hungry but for those who ate before boarding, you're better off sleeping in the bus. For a non stop journey, I suggest taking the Executive Coach from the Jalan Duta terminal. It is a non stop (with a 10 minute toilet break) journey that would take about 5 hours. A cheaper option compared to Nice buses but the comfort and luxury of Nice++ is unsurpassed.