I have some (IMO) really good advice but I gotta take off for now. I'll come back later and update. In short, CN9-A is not bad.
UPDATE:
I'M BACK.
Okay back to topic. First you gotta make sure you have like another 4 million CB to buy a proper XL engine for your Cen/Hunch, because while the stock engine's 64.8 km/h is definitely not enough for a brawel mech, there're heavy mechs that has the same speed (or faster), even with stock engine, but more armor. Even if you find the default speed enough, it's always good to have some extra freedom of weight to install more weapons/ammo/heatsinks (the 3x2 extra slots taken on side bodies barely makes any difference in most cases). IMO a mech is not complete without an XL engine.
With that in mind, next is to determine what role your mech's gonna play in a match: do you wanna be a brawler, a long-range support or a full-spectrum? Based on your choice of mechs I think you're probably gonna be a brawler. Good choice, it's always more fun to be 'brawlin

Also those mechs have enough firepower even without an XL engine.
There're not much difference between CN9-AL and HBK4-SP. There're two energy hardpoints on each of HBK4-SP's arms, which means you have more freedom on the angle of aiming, and you may be able to put larger energy weapons on them with the benefit of XL engines. However, you also risk losing arms during combat, leaving you with only the missiles of your choice. The laser hardpoint on the head allows nothing larger than a Medium (Pulse) Laser, which could be beneficial in some cases.
The CN9-AL has two energy hardpoints on the right arm and two in the center body. The limited space on center body means you can either have 1 Large Laser or 2 Medium (or smaller) on it, and the angle of aiming is limited to the degree that your upper body can twist. On the other hand, you won't lose those firepower until your death. Also, the empty left arm means you can strip off all armor on that arm (which should be more than 1 ton) to make space for other equipment if you so desire.
Other that that there aren't much to say. It's not particular expensive to buy missile weapons to play around so you don't have to worry too much what to put on those hardpoints. You'll finally work out what loadout you like the most.
HOWEVER,
If you're interested in other options, I can provide some theoretically very interesting setups on other Cent/Hunches, if you're willing to save up for the XL engine.
One is a CN9-A with 2x ML, 3x Streak SRM2, 1x LBX AC10 and a proper XL engine. This would be a near-perfect brawler mech with adorable speed.
Another is an HBK4-G with 2x AC2 and 3x ML (or even MPL, theoretically you should be able to free that much space with an XL engine). The DPS of double AC2 makes it even more dangerous than the damned Gausspult.
Edited by Helmstif, 31 October 2012 - 05:46 PM.