Note that the above items are items that can only be MADE by their respective specs. That doesn't necessarily mean the other spec can't USE the item.
Neither spec is especially advantageous over the other; I'd go with whichever spec has items which seem more fun. For practicality purposes, Goblin engineering is superior. Gnomish engineering gets you a teleport to Toshley's Station and a teleport to Gadgetzan. Goblin Engineering gets you a teleport to Everlook and a teleport to area 52.
The Area 52 and Toshley's Station teleports cancel each other out, since they both transport you to essentially the same place, though Area 52 is slightly better than Toshley's station. The Everlook teleport is much better than the Gadgetzan teleport since Dalaran already has a portal that takes players to Tanaris.
So the Goblin teleporters are better than the Gnomish ones. Therefore, for practicality purposes you'd want to do Goblin engineering. However, Gnomish engineering provides entertaining items such as X-ray specs, world enlargers, shrink rays, etc. So what's more important to you: slightly fun but ultimately useless items, or a teleport to Everlook?