If you get a used Skybox, make sure to get one with the BOS. The BOS contains an AFCI device and the upper part of the Skybox will not run without it. There is a bypass circuit described in this forum which was designed to eliminate the AFCI, but you'll need electronics and Arduino skills to assemble one. You'd also lose the benefit of the AFCI safety device.
The Skybox is better suited for a permanent installation with a lot of panels and battery depth. It has high-voltage (600v) string capability with a minimum around 250v, and very high idle draw (like 200 watts).
There's not much advantage to a Hybrid unless you want to sell back to the Utility. Off-grid AIO's like the EG4 6000xp allow a connection to AC power for pass-through, charging, etc. The lower idle draw would be better when you're without AC power on a cart, etc. An off grid device also isn't going to "leak" power back into the grid, potentially getting someone in trouble if they don't have a power feed-in agreement with the utility.