|Pros of X-wing: It fleshes out characters, pretty much shows the whole Galactic Civil War and best of all it's a whole series that doesn't require you to read anything else.
Cons: You may not care about those characters. Wedge is the only one I care about and we get enough of him from the movies and other books. It's not all space battles, but that is a big part and if you don't like that it might be boring. It doesn't have a huge impact on the rest of the EU, in terms of storyline that isn't explained elsewhere when necessary.
I can't recommend starting out with NJO. You've skipped 20 years of EU history, and even though it's summarized you won't know who any of the characters are outside of the big 4. Even if you only care about then, you kind of have to care about at least some of the other characters since a lot of the story revolves around them.
Although the actual plot of NJO doesn't require any knowledge of past events because it's a new thing, I think you're missing out if you don't read at least some of the previous stuff.
It also has a lot of space battles, and IMO the individual books are hit and miss.
I'd say to only read the hardcover books, plus Darktide 1 and 2, Traitor, and maybe Dark Journey.
For the Fate of the Jedi series the essentials:
8. Ascension (unless you care about Vestara, actually this might be skippable. IDK, haven't read the last one yet)
9. Armageddon (presumably)
(for a boring series where nothing really happens apparently you need to follow it pretty closely to know what is going on. I guess that's an improvement over LOTF.)
Oh no, I don't plan on skipping 20 years of EU history. Heavens, no. In fact, I'm finishing up Black Fleet Crisis right now. I've found quite a few books with poor reviews that I've truly enjoyed, so I'm just plunging into them regardless now. The only ones I've held back on are I, Jedi and the X-Wing series.
You all have convinced me to give X-Wing series a try. I think I'll read I, Jedi eventually. The question is whether I should read them right now while I'm still in the era, or if I can hold off until after starting NJO, since I'm anxious to start NJO.