Alice is good if you are short. Alice is meant to ride above a cartridge belt, so it really doesn't ride on your hips. More like on the kidneys on me, i'm 6'4".
The straps are horrible by themselves. They are meant to ride on top of your load bearing gear shoulder straps. If you have load bearing gear they are fine, if not, very thin and very uncomfortable after a few miles.
Only thing Alice does better than Molle is that the frame keeps the pack completely away from your body. Mucho airflow keeps you cooler.
Alice is meant to work with a load bearing harness and cartridge belt, without it, it is a very poor pack.
Molle is much, much better. I really don't understand how some can think that Alice is better. Vietnam era gear is not better than modern gear.
I have used both.
Although i would take a M14 over a M16, but thats another discussion.
Molle shoulder straps are comfortable by themselves. very good padding.
Hip belt is huge,comfortable, and actually rides on your hips.
I think the pack material is more durable than Alice, although the material has never failed on me on either pack.
Don't pay attention to those that say the plastic frame will break on you. A gen 4 frame will not, unless you are throwing them off the roof of a bldg with 120lbs in it. Alice frames break too, if you beat on em enough.
The modularity of the pouches is fantastic. Get a GP sling and a sustainment pouch makes a great little daypack for short hikes away from your main camp.
Havin a separate sleep carrier compartment is great. Don't have to go digging through your bedding to find things.
Only thing that isn't as good as Alice, the pack lies much closer to your body, there is still airflow, but not as much. So you get a little hotter imo.
As far a price goes, if a 20 buck difference is gonna make you or break you, don't eat out for a month and you will have enough for a Molle pack and some pouches.
I see people on here talk about Alice being great, but i went backpacking once with Alice by itself, no lbe, never do that again.
I have been on several backpacking trips with my Molle, it was a night and day difference.