For what purpose? They are two completely different tyres. For winter commuting? Neither- my go-to for winter commuting are Pirelli Cinturato Velos (better puncture protection, lower rolling resistance, and better grip in the wet). For a bike that is primarily going to be used in the dry- GP5000s.
I roll with GP5000 regardless of the season but will consider Gatorskind of I get flats with the former. I've used Gatorskind and they are great at reducing punctures but comfort and rolling, GP is better (though instill prefer the older gp4000).
TBH never used gp5000s but if they are as good or better than the gp4000s then they are a great tyre. Still have a set of Gatorsins on my winter bike and they are good at puncture protection but in my view are both a slow tyre (high rolling resistance) and make your bike just that bit less comfortable, in my view not quite as bad as solid tyres but as close as i would want.
Most Club cyclists that i know have stopped buying gatorskins and now use 4 seasons in winter.
All those criticisms are typical of any low profile tyre like 700x23 or 700x25. You have a low contact area so slippy, you have a harsh ride as run at a high pressure being low profile and weaker puncture protection because the whole load of the bike is through a smaller contact area. Just making the point that size of tyre is a huge factor. Someone running the same tyre at 700x28 or 700x32 might think the complete opposite based on their experience. Really tyre sizes is a critical part of this debate. Then you have to factor in the bike itself. A bike with an aluminum rigid fork will be different to those with a CF fork when it comes to comfort. Someone with a harsh aluminium fork may have to consider tyre comfort more.
I was a strong advocate of Gatorskins for years and found them very good for dry riding and puncture protection. Strange to say in summer rain I found the grip OK but definitely a tendency to slip in winter.
Moved to GP5000s when I went tubeless and find these far superior to Gatorskins.
I used to agree with the general consensus that gatorskins are slippy and uncomfortable but following a long spell off the commuter / winter bike a few years ago inadvertently discovered that they become very comfortable at lower pressures. I continued to run them like that and the following winter they appeared to be a lot more grippy in the cold and wet than previously as well.
The recommended (by Continental) is IIRC 95 psi for 700x28. I inflate mine every three or four weeks to 70 rear 55 front. I've never had a snakebite since running at lower pressure but have had them with the tyres at 95.
The summer bike currently has one GP4000 and one GP5000. They are not the same size. A 700x28 GP5000 is the same width as a 700x25 GP4000. The GP5000 is also a tighter fit.
I used Gatorskins for years and sometimes 4 seasons both ok but found they cut up, especially 4 seasons.
For general durability I would now choose Schwalbe Durano Double Defence or maybe Rubino Pro's, which are an excellent and relatively affordable good all rounder.
I've just binned a pair of 25mm Gatorskins as I noticed a hole in the rubber down to the carcass...not had a puncture though (well maybe one a few years ago), reckon I'd done maybe 4-5000 miles?
Hadn't been particularly slippy (at around 90 psi) but having switched to 25mm Michelin Pro 4 Endurance that I'd had in the spares box for a couple of years (from a Ribble clear out sale way back when), the Gators were certainly sluggish in comparison!
Unfortunately, the 28mm Rubinos also in waiting weren't going to fit under the mudguards