A few thoughts on this comparison:
1) Swinley tends to get more press than Huntercombe. I think this is due in part to Swinley's location. It is in the heath belt southwest of London. It is in the same region as Sunningdale, Berkshire, and Wentworth. Location will either overshadow courses and shut them out from press (see Fox Chapel in Pittsburgh or Fenway in Westchester) OR it will bring them into the limelight. Swinley's location has the latter effect. This statement is no slight on Swinley. However, Swinley Forest in the heath belt will get more attention than Huntercombe in the hills of Oxfordshire.
2) Swinley's look is very appealing. Despite being only 6,000 yards, it is built on a grand scale. Holes such as 7, 9, 10, 12, and 15 possess big features and are just gorgeous. Furthermore, there is a real sense at Swinley that one is away from everything. The train passes by the first few holes, but after that it is off to the woods. I could not imagine a more relaxing place to enjoy a game. Most importantly, the location and land allowed Colt to execute a great routing. One never has to walk more than 20 yards to reach the next tee. The holes sweep up and down the land gracefully. Several external factors conspire to make Huntercombe's routing weaker. These include the road that bisects the course, the flat land after the first four holes, and a small property. Swinley's routing is superior to that of Huntercombe.
3) Swinley's strengths are in its par threes and its long par fours. Colt is a master designer of par threes, so it is no surprise that the five at Swinley are tremendous. The long holes at 7, 9, 12, 15 and 16 are all solid. I could not ask for more out for 400-plus two shotters. Yet Huntercombe overshadows Swinley on the short fours and the fives. Swinley's 11th was one of my favorites, but the third lacks imaginative bunkering or a compelling green. In contrast, the 4th, 11th, and 17th at Huntercombe are all engaging. The green at 4 is my favorite on the property. The 11th is a bit of a black sheep, but I loved the punchbowl green tucked into the trees. The 17th is a superb green complex. One wonders how Park built it in 1901. The fives? Swinley's lone three shotter at the 5th is very inspiring, whereas, Huntercombe's 6th and 16th feature great centerline hazards that challenge all levels of golfers.
4) The greens at Huntercombe are more interesting and wild than those at Swinley. Many in golf--indeed, many on this site--hold disdain for greens that are overly wild. Huntercombe has a few greens that border on the extreme. Yet these are the types of greens that make a golf course great. The greens at Swinley are very good. Yet I got the impression that Colt played it safe on a few of them. The greens at 12 and 15 are phenomenal, but most of the others seem to be missing something. On the other hand, Huntercombe's greens were inspiring from the beginning. The first is the first of several fall-away greens. I can only imagine these greens being maddening in the summer. The valley green at the second, the sidestep greens on three and four, the bold, two-tiered eighth, the rippling 13th, the punchbowl 15th, and the pushed up 17th? All of these captured my imagination in a way that even Swinley's best greens did not.
5) Huntercombe's use of mounds, grass bunkers, and centerline features is very imaginative. It gives the course a sense of uniqueness that I did not quite see at Swinley Forest. Holes like 1-4 and 15-17 at Huntercombe are downright thrilling to play. They gave me a thrill that, for the most part, I did not get at Swinley. Only 9, 11, and 12 at Swinley really compared to those seven holes at Huntercombe.
I suppose I have rambled on a bit. I like both courses a lot. Overall, the quirks, wild greens, and sheer originality of Huntercombe place it higher than Swinley Forest in my book.