A lot of this comes down to gear you already own, like modifiers and speed rings - I've used Speedo forever and almost grabbed a Force ten or 5 several times, but then I worry why they were canned. They seem like a great idea, and the very fast flash duration could be cool to have.
Beyond that, do you want HSS for when you shoot a more modern camera? Do you want battery power? If you go battery, do you want an LED modeling lamp to save juice and still have good brightness? There are a lot of well-regarded monolights out there new, Bowens mount, HSS, battery or not, and so on. Dig through Amazon, Adorama and B&H and check reviews. You may find something new with the power and features and accessory mount that works for you.