I have the 432. It is just enough to fit my Space Marine army because I don't have many large tanks. If you have a lot of Leman Russes, get the 720. If you have a lot of Chimeras and are unwilling to stack them on top of each other, get the 720.

The 352 looks like it's the same as my 432 except with one extra small tray. Small trays are not what you want as IG. One tray can hold like 50 Guardsmen already. What you need is the BIG tray, for your tanks. If you have a lot of tanks, you need more than one big tray, so 720 or bigger is the only option.

I like the 432 because it is skinnier, and I don't regret buying it especially since I have the rare old version with different color and no military straps, but many times I thought maybe I should have bought the 720. If I buy any more Land Raiders or Dreadnoughts I will need to get a 720.