I'm not a big fan of the Sys 1. Have a few and use them but they end up being a bit too shallow for me. I like the 2's the most. Actually have to load up a couple of 3's for tomorrow. Nail guns, sawzall, etc. A 2,3 and 4 would all be good starts. The sys are so much more convenient than the factory Paslode, Bosch, whatever boxes. Load on top of the CT or festool dolly and away I go.
Take a look at a few of the Sys threads where guys have put thin ply partitions in their Sys to cordon off sections. Makes organizing very nice.
Good luck