Thanks for asking:
Just to start with " Any LSP or Sealant is as good as the surface you prepared "
Secondly "You can enhanced the effect by staying under one chain product"
All three ranges are from good brands , I am sorry but I can only comment on Wolfgang as I never used the other two. I am very satisfied with WGDG.3 & I can bet it will come out brilliantly on black colour & I saw one of my friend & PW member @sardarsaeed black civic done by wolfgang products & result was amazing.
Yar durability kee koi gauge nahee , it depend on lot of things , may tuu wax top up hee itna karta hoon kay product ko non-durable honay hee nahee deta 
Sealants are non abrasive
You can compare price from different on line stores
Whatever brand you pick , dont forget to add the same brand paint cleanser/enhancer to the cart
or clay zaroor karna
Else Usman(V1) @vague_one definitely know better than me regarding all three brands 
Good luck & bathreen surface prepare karnaa 
and yes regarding Wolfgang:
Wolfgang Deep Gloss Paint Sealant 3.0 is a water-based, oxygen activated paint sealant. After buffing off the sealant, the remaining coating needs to cure for 12 hours in dry conditions to fully bond to the paint. Exposure to moisture during this time will drown the polymers. For the best results, allow 12 hours of curing time.
Sorry yar pocha sealant ka thaa may nay ground zero kee taraf reverse gear laga dia :-#
Anyway hope it helps