First off, throw away your preconceived ideas since your information is probably woefully out of date. I say that based on your comment about rangers being 'badass with swords' and SKs being 'outcasts'. That may have been the case back when the AA system was new (when you last played) but that is by no means the case today.
Today, the best grouping tank class is the Shadowknight. That's not to say the Paladin or Warrior "suck". They do not. But the SK's abilities and development options make for a very versatile class that can perform several roles that groups tend to value highly (tank and puller being the most obvious).
Bard is a class that is easy to play but damn hard to play well. Many people use boxed alt bards with a single playlist (song sequence) because the class is such an effective force multiplier. However, while boxing the class is okay and gets decent results, playing the class actively requires a lot of attention. Since Bards can typically do so much and fill so many roles, your song lineup will be extremely important. But if raiding is even a consideration, this is probably the class you want to play. You can never have too many Bards.
Rangers are extremely versatile and work well in solo, group, and raiding environments. That's been the case for years so the problem you may run into is one of overpopulation. It's a great class and everyone knows it so everyone has one (or so it seems).
Necros are very powerful, still. The only problem I think Necros might have is their burst damage doesn't really get good until later in life (70+). Burst is important in groups since many mobs won't live long enough to make dots very efficient. Pre-75ish, the game has inflated to such a degree that group fights that were lengthy when they were new (say, mobs in Crystallos) are no longer so the power of a Necro bleeds away as the fights get shorter and shorter.
Here's the bottom line. Follow Touchin's advice and play them all to 55 (not 50 since you don't get many of your better tools by then) or so then pick the one that's most fun to you. Good guilds recruit PEOPLE, not classes (because a good player is a good player regardless of what class they're playing and modern MMO raid forces need good players more than anything else) so your raiding life shouldn't totally depend on what class you are. Play what you enjoy most and everything else will fall into place.
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