From what i gather vcds allows for more changes with one off spend. Whereas with obd you can make some changes but for many others you have to keep paying or biy credits ie ongoing expediture
I have just invested in a OBDEleven device as my current Ross Tech cable won't suit my next vehicle on order.
The functions on the OBDEleven Pro match that of the VCDS in allowing coding changes but in a slight different way. There are posts which detail the screen/tick boxes needed over VCDS coding. Fault identification and clearing is miles ahead of Ross Tech in ease to use. All in all a lot easier to use if you are unfamiliar on how long coding works. There appears to be more information now on OBDEleven in forum land so I guess more are coming on board and sharing what they find.
There are pre-set applications available which require credits to access but you can get daily credits by watching a few ads on the mobile app. You don't need to spend any more once you have had the initial purchase. Basic applications are 10 credits and more complex ones 100 credits. New application are available on a regular basis, example last night about 5-6 new basic applications appeared for each of the 3 vehicles I need this for.
The handy thing about OBDEleven is it is on your phone (android) and as long as you have internet access you can access the program. The device can remain connected to the vehicle as it talks via bluetooth.
Any actions you make are uploaded to the server and it maintains a history of your vehicle (or vehicles) for quick reference.
The OBDEleven is value for money considering the cost and I would recommend it to support the VCDS cable. In my situation a replacement cable from Ross Tech couldn't be justified now it is limited to a couple of VINs so hence why I tried it. Also because you are only provided with a dongle that is linked to the phone app every time you open the app it is updated so you have the latest version.
If you really want the app allows a range of gauges in real time to monitor your vehicle's performance from torque to oil temp, battery life to fuel/air ratio.