The other day, I popped by Fitness First marketing booth to check out the prices since they don't provide the information online and expects you to make an appointment with them so that they can try to hardsell you the package.
Prices that they quoted me -
145+ monthly for a commitment of one year (Corporate package)
139+ monthly for a commitment of two years (public)
149+ monthly for a commitment of one year (public)
Information that you should note - Each year, they may increase your fees up to 3% and it is written in the contract that you will be signing.
I'm not sure what others are paying for their packages but when I signed up in 2014 (last year), i paid 133+ monthly under the corporate plan.
They can always justify that they have more clubs in Singapore, which is why you need to pay a premium of that price but looking at the crowds in Fitness First nowadays, I think it is not a worthwhile investment. Of course, that's my opinion and you are free to make your own judgement.