If what you want is a consumer grade machine, I would go to option B. I would also find/use one of the newest cpus as they are more electrically efficient than the older ones. More bang for the buck so to speak. It is hard to beat the reliability of the Xeons.
Cheers

Check out the other thread here I just started regarding the Lenovo small desktops that have the i7-7700T chip at a ridiculous sale price for the next few days.

I went with the 1700 over the X. Unless you plan on overclocking, which I don't, I have heard the x is better in that respect. But the 1700 TDP is only 65w, vs the 95w of the x, and you are only losing 400MHz.

This might surprise a few people, what would I recommend for an efficient build? Ryzen 5!

It's no secret that I've been through a torturous year with a Ryzen 7, many new sweary words were learnt along the way as I swapped item after item, someone eventually suggested the chip might be the problem - nah they just work or they don't work - hoooonk - wrong, very wrong, eventually I marched up to the retailer that I bought it from in Angry mode and asked them to look at it, they tested it and said - it's fine and after much barely contained rage they agreed to send it to AMD and as a sign of good faith (probably to get me out of there) they lent me a Ryzen 5 1600, took it home slotted it into my system and boom - perfect, runs at 3.85Ghz like a champ all day long and chucks out about 100k points a day - and yes thats a lot more than my beloved 3930k's.

Much to AMD's credit they got in contact to ask me what I was using it for and they said fine we'll stress test it heavily, guess what they ended up sending me a new one because my original one was faulty.

But the 5 is the absolute bargain of the century, it's sat in an Asus 250 motherboard (dirt cheap) the chip itself was (dirt cheap), the whole system is pulling just over 100watts and pushing out stratospheric numbers using ubuntu. The only overkill component is a Samsung 250Gb NVMe SSD but that's probably contributing very little. When I rang said retailer to buy the Ryzen 5 because I wanted to keep it they said forget it, you've had a load of grief, have it on us.

The Ryzen 7 is also behaving impecably, right now it's at 3.9Ghz and sitting at 47.75ºC, unfortunately it's hampered by Windows 10 so I don't know how much it could do under Ubuntu.

When my favourite MMO shuts down I'll have no reason to not put Ubuntu on it then

So in the space of a fortnight i've gone from loving Intel to lusting for Threadripper,but my wife would relieve me of certain parts of my anatomy, just need to get her out of the house for a few days..............

Don't know what your preferences are. But I'm going to get myself a used Workstation, which come cheaper than top of the class computer. & upgrade them to highest spec within a year.

All together cost of a newest grade computer. But much more stable & much more heavy weight for crunching. ;)