1. Which FITS better. If one doesn't fit, why the F would you buy it. I had a Air wolf with the big bottle and whilst it was a great accurate and near silent hunter, boy was it a pig in the field to carry and point. It was also the version that back fed pellets into the breech housing thus jamming the bolt usually at very critical moments.
I now shoot a modified HW100 Sporter and its a keeper. 4 x 14 shot mag's and I can cant carry any more dead things especially if it has to be gutted etc.
2. What job/s does it have to do and which is better for the task/s you will ask of it.
Again, the 100 if a target rifle, a plinker, a hunting rifle (its number one use) and an HFT gun (its former main reason for being) I does ALL of those really well.
I will get other rifles. I have an FAC Air Ranger which is also brilliant but its a gun I only really shoot from a vehicle. Again its too big for wandering around with.
Both of the guns you mention are good rifles. Both have respective +'s and -'s and the order of those becomes pretty much dependent on what YOU want.
However, if it doesn't fit there is little point in looking at what jobs it can do.
Best advice is try both and shoulder them with your eyes shut. With the 100, they really really benefit from selling the steel and buying an alloy cylinder. balance is improved as I do not like front'ish heavy rifles though some do. You want to feel that the position and the ergonomics work for your body and shutting your eyes makes you much more aware of this difference between the guns. Weight, Balance, Length of Pull, operating the cocking mechs, the trigger......its all info that your body has to work with and if it don't feel right its because it isn't right.
What is the saying....marry in haste repent at leisure
In a battle of wits I refuse to engage with an unarmed person.
To one shot one kill, you need to seek the S. Kill only comes from Skill