Do you really need to ask which one? I'd hope not, but just in case, I'll clarify. I snagged a key for the Halo: Reach beta late last night from Bungie's site, it's a lot of fun to say the least. At this point, I'll just post a few drabbles on various aspects of the game.
The Assault Rifle: Is perfect. Bungie has really struck a nice balance with this weapon. It never feels too powerful, or too weak, not to mention It's also surprisingly accurate. Still, don't expect to kill anyone without first emptying 3/4 of a mag into them first.
The Magnum: A nice back-up weapon. The magnum serves its purpose as a back-up weapon well, however, despite being quite a bit more potent than its Halo 3 counter-part, it still doesn't quite function adequately as a primary weapon. Generally being outclassed by the assault rifle at close to medium range, and outclassed by the D.M.R at medium to long range, it's probably best to keep this weapon as a back-up weapon and little else.
The DMR/Needle Rifle: Similar in function, with a few exceptions. I've found myself leaning towards the DMR for some reason, but in the end the difference's between the two weapons are generally cosmetic. Expect four shot's to drop a shield, and one follow up shot to the head to tie things down.
Melee: Is a little overpowered. I haven't played Halo 3 in a bit, but the delay between beat downs seems a little short, I kept getting melee'd twice in a row in quick succession with almost no time to respond. I'd like to see a little more of a delay between each beatdown in the future.
New Game Types: Kinky. Most of the new game type's are pretty fun. Headhunter is a nice chaotic mess, while stockpile is a really nice take on capture the flag. 'Covy' Slayer is interesting. Since everyone is an elite, they take more damage and regenerate health. The health boost make's things a bit different since obviously, it takes longer to kill an enemy. Regardless, firefight's seem a little dragged out with the health bonus. Evade is pretty fun to use though.
Armor Abilities: Squat. The armor abilities are pretty neat. Sprint is my favorite at the moment, since it can get you out of a pinch really quickly, and throw off would be snipers, etc. Armor lock is really useful when playing team game types, since you can use it to become a distraction while your other teammates mop up the opposition, it doesn't seem overpowered, but I guess we'll see. The jetpack is pretty self explanatory, and I'm not sure how I feel about active camo yet.
I apologize if this seems rough, and for my lack of proper spelling, punctuation and grammar, it's late and I'm tired, and I'm not bothering to proof read this.
I will update within the week...probably. It's not like anyone read's this damn thing.