I have worked on a substantial number of these vehicles. 2WD , hands down the the VC kit is the way to go. Improves handling, improves roll, yes, the front struts bottom out once in a while (and make a big bang) but that is rare - you really have to hit it hard to make that happen. I've put 5000 miles on mine and heard the bang twice and I'm off road a lot. The blue spring kit is a bit better / easier to install than the red spring kit and it causes less issues. The red kit requires some mangling of the shock tower surround and its not easy to do with little clearance in the fender well. Also the blue springs are a LOT easier and safer to assemble. I don't recommend DIY spring compressors anyway - but the red springs you definitely do not want to use the DIY compressor kits.
AWD - Ford did not do a good job on design here. Lifting this design causes severe wear on the CV assy. I would avoid it unless you want to be tearing your front end down every 5000 miles. I am not a fan of the Sprinter due to the constant need for maintenance and repair - but their 4WD design is superb compared to the Transit and the Benz factory lift is actually pretty good.
As far as installation - pre-build the struts - that will save you many hours. Even with a full lift and shop full of good tools, there was nothing easy about this job. Dear God R&R of the strut nuts was half of our time spent. Good job Ford... LOL. As far as suspension work goes - it WAS easy - especially since we only worked on new vehicles - but that said, its still a tough job. Start to finish with pre-built struts it took me exactly 4 hours front and back. I spent one solid hour on the strut nuts - ridiculous. If I had not pre built the struts I would have easily doubled that time.
The AWD install flat out is a PITA. Its also very easy to damage the CV bearings. After watching videos and looking at a customer's van I decided it was not worth the liability for me to do it. If it was my own vehicle I probably would have done it though.
There is a reason most shops charge $1K in labor to install the 2WD lift and $2K for AWD. Its a lot of work and liability if something goes South.
I have the 2" lift front and rear on my 2WD Transit along with bigger tires - and I Love it. Made a HUGE difference and I can go just about anywhere.