It is Royal Portrush G.C. not Port Rush as I spelled it above.
Which did I prefer? That's a tough one but if you're asking me not to hedge I would say I preferred Newcastle! But the reason would probably not be because of a straight architectural comparison or a comparison of the inherent interest of the layouts for golf.
Both courses have so much going for them in so many different ways I wouldn't even make an architectural comparison just to try to determine which was better. But I would be glad to make architectural comparisons as to why both are so good and also quite different from each other in interesting and subtle ways although both are Northern Irish seaside courses. In a quick sentence, to play either course well, in my opinion, you have to play them quite differently, or at least you certainly can!
I would say I preferred RCD only because its conditioning was just about prefect in every conceivable way for what the course is! To be fair to Portrush its greens had been recently aeriated and sanded and were more inconsistent to play and much slower.
RCD's fairways and greens were firm and fast and true as could be. And the thought and maintenance that went into the approach run-ups and very tight and sometimes massive chipping areas in interesting places around the greens was a total joy to try to figure out and play. When I say the "interesting areas" of tight lie chipping I really mean that too because they certainly weren't everywhere surrounding the greens and after a while that becomes a design feature you very much pick up on and need to notice in the context of where to miss the ball, particularly in very windy conditions.
I would also think that Portrush might have twice the elevation change on the site as RCD, and, if not, the elevation changes along many of the holes at Portrush are much greater than RCD once you factor out the unique perpendicular and enormous topography that creates the total tee shot blindness that RCD must be famous for on many of its holes. Three of the par 3 tees at RCD are on very high ground in relation to the rest of the hole though.
RCD has far more bunkers than Portrush and it's far more penal and difficult to avoid. RCD's particular shaped bunkers are also about the most ruggedly beautiful in the world! On the tee shots, interestingly, RCD's bunkering is almost always on or near the flanks of the fairways but there are so many individual bunkers at RCD they are hard to get out of your mind. Portrush's tee shot concern is a bit more about avoiding flanking mounds or internal fairway slopes and contours that are dangerous or hitting the parts that are benefical. Portrush uses enormous natural mounds and hillocks that pinch in on tee shots and on green approaches. RCD has plenty of this but probably not as much. RCD does, however, seem to have something at some point on almost every hole that makes you think of either gearing down, gearing up or getting really pinched in! Maybe they both have a lot of this but it seems Portrush uses the natural topography along its holes and RCD uses bunkering more! But maybe RCD has almost as much pinching topography. RCD does win in the bunker category though! It probably beats almost any course in the world in this category. Both courses have about 3-4 holes that have some of the most thoughtful approach bunkering right in the middle of the fairways too.
The approach shot architecture at RCD is lower profile than Portrush, particularly at the green fronts and allows the golfer to play probably a greater variety of runup shots. Many of Portrush's green entrances are upslopes and would lead me, anyway, to try to fly the ball to the fronts of the greens more or hit something very low to get it on the ground well back and running up the approach inclines! When you factor in high wind conditions Portrush might actually be a little harder to play because of more of this.
But I might have to take even that back because although RCD has low profile approaches and probably much longer ones on some holes, the subtle contours and low level mounds and humps and bumps on its approaches and how they tie into the really interesting contours of the greens vis-a-vis where the ball ends up on the green could be about the best I've seen in the world.
Both courses have a considerable amount of quirk and both have holes that do have certain pars although the best policy (in the wind anyway) is to just do the best you can and to really think about how to minimize some kind of disaster! Both have par 5s that can be like par 4s and RCD has a par 4 that is really a very long par 3! But each has its own interesting strategic price to pay for aggressiveness and stupidity.
Both courses are extremely beautiful in their natural ruggedness although Portrush looks more rugged while RCD has the captivating Mountains of Mourne directly to the south when the golfer turns that way.
Both are certainly in my very top favorites in the world and when I finished playing RCD the thought did occur to me that this might be just about my favorite course right up there with NGLA and Pine Valley. I say this despite the fact that a few holes are probably odd or unfair to the modern golfer. I must say in the high wind I really don't know what I would try to do on the tee shot on #9 RCD and yes the pond on #17 is odd but the hole does have a great green surface, dangerous greenside bunkering and some great run-up shot options.
Some of the tee shot blindness at RCD is alarming but I do love it! If you really don't like or don't understand blindness I would advise just not going to Newcastle.
So although I say here that I preferred RCD to Portrush, it's really all in the "maintenance meld" that turns the lights up full on a course's inherent design. If Portrush had more of it than RCD instead of the other way around maybe I would go the other way. But like I found out a couple of years ago at NGLA this "maintenance meld" thing is really important--really important! Look at what it's done to Huntingdon Valley too!
Anyway, they are two great golf courses and if you're interested in some great architecture and design concepts both are mother lodes!
#5 Dunluce is a world class hole, one of the most interesting I've ever seen, and so is #8 and many of the others. Again, RCD's #13 is probably in my top 3 par 4s anywhere now and so is #7 for a short par 3, and RCD has many others too!
Somebody asked about the Valley course at Portrush and it too is a wonderful thing to play and see although not as sophisticated as Dunluce. I would also call the Valley a golfing ground, if you know what I mean, where Dunluce is more a course with very individual and separated holes. The Valley is probably a lot like things used to mostly be long ago!
The Valley's #2 even melds so startingly into Dunluce's #17 that my partner got hit on the thigh and dropped by a full bore drive while walking the first half of #17. But he's an old Irish rugby player and he just got up and kept going.