All of these use the same hub, so, no worries about getting the right hub. The question is, which remote?
You can find a Harmony Hub with the Smart Control remote for as little as $60, new, if you shop around - maybe even less. This is the remote I recommend. Here it is for $51 refurbished. Seriously, for the price, this thing can't be beat. It's fantastic.
My advice is to avoid the Companion remote like the plague. The Companion is the same as the Smart Control, but it's uglier and it comes with six extra buttons at the bottom. Those extra six buttons may seem like an asset, but they're locked down for absolutely no freaking reason. They only work with specific smart devices, and only in specific ways for those devices, which in some cases make no sense. I found it so infuriating that I returned mine. It's obnoxious to pay so much for a remote that you can't use the way you want to. Note that the Harmony Elite remote which costs $100 more has the exact same buttons but they're NOT locked down. So, why are they locked down on the Companion? I'll tell you why: Because Logitech is inept. I love the Harmony system, but this remote is awful. If you do a search on the Logitech help forum, you'll find that people have been begging Logitech to fix the firmware for this remote for years, but they're ignored. My advice: Don't buy it.
You mean this? Logitech 915-000194 - Harmony Smart Remote Control with Smartphone App - Black (Renewed) https://www.amazon.com/dp/B00ZYIFXSM/ref=cm_sw_r_cp_apa_i_Ik16Db0QHWB7J
The Smart Control remote is sold either with a hub or as an add on for those who already own a hub.