I am not a fan of soaps. Creams work better for me. I am especially not a fan of woolfat. I find it has a drying quality and is not slick enough for me. But I am probably in the minority. I am a huge D.R.Harris fan. They have never dissapointed me. The only trouble is they are expensive. More than most and are often avoided. If they were a relative bargain like Taylor's I think they would get far more attention. Their products are excellent. Their Arlington soap is wonderful both in quality and aroma. One of my favorites in the soap world. But the Arlington cream is my prefered cream. I've been using it for 10 years, way before I got into DE shaving. In the end you could purchase both and save yourself the trouble. You're likely going to get them both eventually anyway.
DR Harris is top notch stuff. While it may be expensive, the soap lasts forever. I can't comment on the cream but the per shave cost is overall pretty nominal. The soaps lather like a champ and smell great.
I'm afraid its difficult to compare the two...they are both fine soaps and worth the money, get both you will not be disapointed. The DRH has a better scent and will last longer hence it's price. The MWF is not triple milled so will not last as long and there isn't much of a scent but it's a great performer if you have sensitive skin. I like one because of the scent I like the other particularly because of how it makes my skin feel.
Haven't tried Arlington, so I don't know what it smells like. MWF has a nice clean, linen type smell and has great lather, but for me it is tough to lather. DR Harris Marlborough produced lather as good as MWF, but was easier to lather. I would say get the one that has the better scent to you.
I have and love both of them! I would say go with the one that you like the scent better. Like others have said MWF has a nice light clean soapy smell and Arlington has a nice clean citrus masculine scent.