If you're doing this for profit on other peoples' vehicles then you will need to spend a lot more money to cover all bases.
If you're doing it just to cover your own vehicles then you need to consider those specific vehicles.
At the very least I would own a wireless dongle type that connects to your phone (wifi for Apple or bluetooth for Android), that you leave in the glove box so it's always with the vehicle. I would not want to leave a $400 scan tool in the glove box of any vehicle, let alone buying multiples for all vehicles.
I bought two different $10 dongle type where the sellers were basically lying in stating that they were compatible with all '96 or newer OBDII vehicles when in fact they only worked on mid-2000's and newer vehicles with CAN protocol.
After wasting time on those I got a BAFX which does work on the other protocols like J1850:
https://www.amazon.com/dp/B005NLQAHS/?tag=atomicindus08-20
You stated it seemed like a hassle(?) to input connection info for a wifi version but this is not really a big deal. It's usually a one time thing. With the bluetooth versions of these you would enter a pairing code on your phone or tablet, etc, which is usually something like 0000 or 1234. It literally takes 20 seconds or less, once.
Now on the other hand if your vehicles are all new enough to be CAN protocol, you can get one of those tiny translucent blue dongles on ebay for around $6 delivered. The cheapest price on ebay may fluctuate daily so I'm not going to hunt down the best deal at 7:46 on Sunday, but they look like this one on Amazon and you might want to spend $4 more to get it in a couple days (with prime) instead of in a month from China:
https://www.amazon.com/dp/B01HXGX8V6/?tag=atomicindus08-20
I suspect many people who think you get a lot more with an expensive scan tool, are not familiar with the capabilities of these dongles. They do NOT only tell you OBDII fault codes. They are capable of showing real time data on many parameters, even while driving. Of course they cannot do most manufacturer specific fault codes but if you happen to own a Ford, the app like Forscan can do many of those.
Just one opinion, but I would get one of those even if you end up getting a more expensive one too. I'd hold off on the expensive one till you find a specific instance where you need it. Do not use the software CD that comes with them. Get Torque or another app from a trusted app store.