You are not doing a proper comparison by conveniently leaving out a number of key factors in your decision making.
(1) the USB modem from Maxis is on a rental basis, you do not own it. You can buy a HSDPA PC Card modem for less than RM 400 now in lelong.com.my to be used with Celcom 3G. And you own the modem.
PC Card is PCMCIA Card Type, Which,my notebook only supports expresscard. It is because of rental I decided to take the maxis plan.
(2) the minimum contract period for Maxis is 18 months. If the service sucks, you have to transfer your account to someone else. Slightly more difficult to do than selling off your HSDPA modem if you had gone with Celcom. With Celcom, there is no minimum contract period. If you don't like the service, terminate it next month, then sell off the modem. There are a lot of potential buyers in lelong.com.my.
heh, this cant help 
(3) as someone has pointed out before, you can do an easy payment scheme with IzziNet. Yes, you promise to pay them 12 months in advance, but by signing up for interest free monthly repayments with participating banks, you only pay on a monthly basis - no different from Maxis or Celcom in this regard. If you don't have a credit card from one of their participating banks, get one, credit cards are free nowadays anyway.
if i take easy payment, it will add more monthly prepayment to my expense. (RM 99 for Celcom 3.5G, probably RM100 for easy payment) so, maxis is the simplest and easiest solution for me.
There are of course other more minor issues with Celcom's 3G service, such as having to go through one common gateway, but for the majority of users (?) this is not a major consideration, I think...
The biggest issue with many Maxis broadband subscribers now is that they find the service sucks, but find it hard to cancel because of the minimum contract period, and finding someone to transfer the account to. If you're sure that the locations you will mainly be using the Maxis service has sufficient coverage and gives you a good speed, then go ahead. Otherwise, it's a game of chance, as prasys has found out. Now he's stuck with Maxis for the next 17.5 months

and, my ultimate purpose of broadband is to send my business emails, research, download artwork from client at megaupload (i could get 200kbps btw by mgaupload), and mobility coz i always travel.
the solution that maxis provided is suited me well. you just need to find yours.