I'd have to go with (In no particular order):
Alfred Hitchcock - Yeah, many have listed him and with good reason. Rear Window? Dial M For Murder? North By Northwest? He's easily in the list. Plus I love the "Spot Hitchcock" game in most of his movies. It's a great way of getting the audience to pay attention.
Spielberg - Another great director and a common choice. He's far from a pretentious git's choice, I feel, but as far as simple, fun family films go, you don't get much finer a choice. Even War of the Worlds, which was greatly slated, didn't seem half as bad as people made out. His best stuff are really up there with the best though.
James Cameron - Aliens, Terminator, The Abyss, etc etc? He's a sure fire hit of building suspense in his movies and a great pioneer of technology (he knocks Lucas out because he can both utilise special effects well and actually direct/write with certain quality too.
Now I'm struggling...next up there's a bunch of hit and miss directors, like Rob Reiner, John Carpenter and so forth. I'm pretty mainstream a movie goer, so a lot of these snobby "we're film buffs" directors just don't appeal to me.
I suppose next I'd have to go with
M Night Shylaman. Even though for some reason he's constantly labelled a hack, I just don't get it. He's made about 5 known movies, three were good to great, two were poor. That's pretty good for a director, I feel. He's brought about a new personal style, which sadly has been being poorly imitated ever since, that I tend to like. Another director good at slowly building suspense, like all of the ones previously mentioned - something I think is what makes a great director, instead of these "action action action" pratts of recent times. This guy needs to prove himself by getting back on track with quality and doing a few different movies.
Lastly, even though I'm sure that there's more that could make my cut, I'm going to go with
Paul Verhoeven. I can only really name four movies he's done, but they've all been pretty high quality. He likes his action and he likes his gore. I like action and I like gore, so I like his movies. :P Oh, he also does them well. Pure, simple entertainment - you don't get much better.
Hopefully these guys have still got many years in them before they retire/snuff it, so that we don't have to depend on hit and miss (mostly miss) network exec pushovers and flavour of the month directors like Michael Bay, Gore Verbinski, Len Wiseman, Lee Tamahori and so on - all who have made their fair share of total crap, and, perhaps, got lucky with one or two movies between them.