AIM every time , sure it costs a bit more , but you get what you pay for .
As for room , you will have plenty , pockets galore , straps and pocket inside , ruck sack straps if required .
Tough a old boots .
I can get my Pardini with the mounted Sightron 10-50x60 in it. , but not with a side wheel fitted , if you get the longer AIM bag , you can fit a rifle with scope and silencer on it .
Pockets are well big enough to take pellets , small air buddy bottle , bipod , packed lunch , even small flask .
Go for the AIM you won't regret it .