One thing I didn't hear you talk about is your needs and general budget. For example, we chose an H model due to our desire for the larger vertical storage. I store my bikes upright in one of the bays using fork mount points screwed into the joey bed.
Some people really value the higher ceiling space in the X.
Also consider maintenence. For us, we preferred Marathon partly because we're west coast based with usually annual trips thru Oregon and liked the availability of Coburg. We know them well, stay in the parking lot frequently. Liberty is a more east coast based company. But of course there's many 3rd party companies who also can provide service for whichever you choose.
Then of course there's look and feel. So I encourage you to explore what you need to help drive that selection process.
What an adventure, we hope you enjoy the shopping journey as much as you'll enjoy whichever you end of selecting.