Tenjen, in the end there becomes one question, more or less consumables?
(Be aware I talk in Trends and Tendencies, there are exeptions to almost all cases)
This is not like weaponsmithing or Armorsmithing(but I will admit the 300-375 push for eng is way harder than the 0-300 gambit), I have always found Engineering to be a reletivly low stress profession(mostly because Engineers are not AS fixated on making Coin with the trade and are out to serve themselves with it)
First thing to keep in mind about the two diffrent specs, the diffrences are huge at level 225-270 then they almost become the same trade again untill you get a few diffrences in the outlands. I am going to make a bold statment, and i am sure some folks will not agree with me but out of the "First" batch of spec spific items, No (BOP) Spec spific peice of gear will sevirly alter your gameplay at level 60 or beyond(the new stuff is a slightly diffrent story, mostly due to the fact i do not have a goblin engineer past 315, only gnomish)
So it is all about some fun, Goblin Spec tends to focus on blowing crap up(and I like that) While Gnomish tends to build overcomplacated ways to hurt our targets.
One thing to keep in mind is the trasnporter, Each spec can make 2 transporters, that take you to 2 seperate locations, for example goblin spec engineers warp to everlook while gnomish spec goest to Gadget....
Unfortuanly i can not tell you what spec is Better,Since I think there is little diffrence byeond symantics and a few items that become quickly outdated(why obsess over the Gnomish Death ray when you can do the same dammaeg with a WF strike?). if you are just fishing for a awnser? Go goblin, they have some fun explosives.