Here's my extended experience with skins...
Personally, I've seen too many issues with G3 skins of the past... the glue has too often turned into a giant goopfest and you'll find residue boogers all over your bases. The new ones are supposedly redesigned, but I think the glue is the same.. as it's still not super consistent and will leave residue on your bases if it hits a temperature that's at all outside of it's comfort zone.
I don't really mind the scala tip for skinning, but it is a bit more frustrating to pack into your jacket for quick laps, and it's also not quite as easy for getting your skins properly aligned when applying them.
The Mohairs seem to glide pretty well, but the Ascensions, and in particular the Ascension High Traction (or Ascension+ Grip as it's now known) aren't very good at gliding, even after you candle some wax into the plush.
Black Diamonds have been pretty damn good for years... heck, about 8 or so years ago they had to change the compound because it was a bit too hard to get apart... and yet they only made the skins better. I have used both vintage ascensions and modern ascensions and the new ones are way easier to pull apart while still being plenty sticky to the base and not leaving residue like G3's
The plush is phenomenal from BD... Either the Nylon or the Glidelites are good... The Glidelites are the best climbing mohair mix skin I've used. Even better and longer lasting than G3's. I haven't used the Ultralites, but I've cut them for customers, and they're probably the only ski that you NEED to use the BD skin cutter because they'll gum up every other brand. The tip and tail are okay. I don't like having to install the tips as it's a bit of a pain in the ass, but if you buy an STS kit that's pre-sized, they're a breeze. They have a crappy skin cutter, so go to your local shop and ask if you can get a G3 or pomoca cutter for your skins.. unless you get the ultralites.
Contour skins, which are made Kochalpine in Austria and distributed by CAMP USA seem alright. I know people who really like them, but they also seem like a pain in the ass since I've heard from plenty of folks that the two layer adhesive that they use doesn't seem to stick very well after a while. I've also heard that they can be fully 'replenished' if you clean them with basecleaner, or the solvent they provide.. They have awesome tip and tail clips, in my opinion. I believe Black Crows uses them for their pre-cut skins on their skis.
Pomoca's are pretty damn good... probably the lightest plush out there across their whole category and the glue seems okay. not as long lasting or holding as much integrity as BD, but seems alright. at the very least it will become not very sticky, rather than goopy like G3's. From what I understand, in Europe they can't use certain chemical compounds in skin glue for environmental or health reasons, so they aren't ever going to be quite as sticky or confidence inspiring... and i've noticed the glue tends to 'pill up' after a while and degrade a little faster. None-the-less i've always had generally good experiences with Pomocas. Many brands use Pomocas as their white label skins... particularly K2 and Voile.
I used a set of ClimbingSkinsDirect.com skins a few times and they seemed alright. The glue was SUPER sticky.. kinda like the old ascensions used to be... which makes sense since they are owned by the guy who used to be a product engineer at "Ascension" before they fell under the Black Diamond umbrella. They still didn't leave residue though, so that's good. I'm not a fan of the vintage style tip design I used but I guess it works alright? Definitely the cheapest worthy option I've encountered... You have to fold the tip through the loop and stick it to itself to hold itself in place, like the ascensions of yesteryear. BCA uses these as the basis for their white-label skins.
Montana also makes skins but I've never used nor cut them.. They're pretty rare to find in the states. However I think they make the skins for La Sportiva, and I've used those. If they're indeed Montana made skins, they seem fine. The plush was kinda thick, but glided really really well while being pretty lightweight. the tip is super solid, leaving little room for snow to get under the skin and bunch up while trailbreaking or gliding.