OK, well the Ghost type is an interesting and very diverse type. Giratina is its only legendary so far, but you do say no legendaries, so excluding that here are some other good ones.
Also is this competitive or in-game? This is kinda important, as different Pokemon may be useful compeitively, but take too long to take down the enemy in-game (especially stallers - do you really want to Toxic-stall everyone in-game???). The opposite is also often true, where a good Pokemon in-game is useless competitively.
So as for some good Ghost types:
Sableye: Probably better competitively than in-game, it is one of three Pokemon lineages to boast no weakness, prior to the introduction of Fairy in Gen VI, at least. Its ability Prankster is what makes it better than its mediocre stats suggest, and it has the move set to abuse it, wth moves like Will-o-Wisp, Toxic, Recover, Substitute, and also access to Night Shade and Foul Play to make up for its bad Attack stat.
Chandelure: My personal favourite Ghost type Pokemon. It has the highest non-legendary Special Attack in the game and can absolutely wreck anything. It is part Fire, and so gets Flamethrower, Fire Blast, and Overheat, as well as Shadow Ball, for its STAB moves. Other moves for it include Energy Ball, which can deal with the majority of its weaknesses, Pain Split, and Will-o-Wisp.
Gengar: The good old Gen 1 Ghost type. It has high Special Attack and Speed, so can do some real damage in-game. As for competitively, it usually uses Substitute + Disable, but you try some other things with it if you want. It gets STAB Shadow Ball (obviously) and Sludge Bomb. Sludge Bomb is usually only worth a mention if you are playing Gen VI, though, which you aren't. Still it is something to keep in mind if you want a Ghost in X and Y. Gen VI also gave it a mega form, and it was one of two Ghosts to get one. Again, this probably isn't relevant since you aren't using Gen VI.
Spritomb: The other Ghost/Dark type, and so a second of the Pokemon that has no weaknesses prior to Gen VI. Its stats are better than Sableye's, but its ability is less useful. Still it has decent enough stats, although its Speed sucks. Still moves like Shadow Sneak and Sucker Punch (both of which are STAB) negates the need for Speed. It also has access to Will-o-Wisp and Pain Split, like any decent Ghost type, but not really that many coverage options.
Mismagius: Another decent Special-Attacker Ghost type. Its Special Attack, Special Defence, and Speed are all pretty high, but try to keep it away from Physical attacks, as it won't survive many of them. It has decent coverage options, too, including Thunderbolt, Power Gem, and Energy Ball.
Cofagrigus: Most of the ones mentioned so far are straight up attackers (except Sableye), so here is a wall. Simply put, it is a very good Physical wall. This is definitely one more suited to the competitive scene, however. Give it things like Toxic, Substitute, and Pain Split, probably along with Shadow Ball to have something to attack with if you're Taunted. Will-o-Wisp is another option to completely cripple physical attackers.
Dusclops or Dusknoir: Both good Pokemon, and both with different niches. Dusclops runs a very good Eviolite move set, and can be used as a wall similar to Cofagrigus. Its evolved form obviously can't use an Eviolite, and is usually a physical attacker, often using Subtitute + Focus Punch, along with moves like Earthquake and Shadow Sneak. Sometimes it might use the elemental punches instead.
Jellicent: A good Special wall, with high HP and Special Defence. Giga Drain will also help it recover HP, as will Water Absorb, if you have good prediction when switching in. Maybe give it Scald for the burn chance, recover, and possibly Substitute, Shadow Ball, Toxic, or Ice Beam. Your choice.
Golurk: A good physical attacker. It can make good use of either No Guard or Iron Fist, No Guard allows it to abuse Dynamic Punch with perfect accuracy, while Iron Fist powers up Focus Punch, Hammer Arm, and the elemental punches if you prefer to use that.
Now that I have gone through most of the Ghosts from Gen V or earlier, I will add a couple from Gen VI, just in the interest of being complete, and if someone (besides the asker) is interested in Ghosts in the newest generation.
Trevenant: My personal favourite of the Gen VI Ghosts. It can do Substitute + Leech Seed, or it can be an all-out-attacker, or it can run a Trick Room set.
Aegislash: Possibly one of the hardest Pokemon to predict, and yet you can probably guess its entire move set whenever you see one: Shadow Sneak, Swords Dance, King's Shield, and Sacred Sword. Even though its moves are guessable, what the person using it will do is not. It is a very good Pokemon, with both high defences and high attacks, depending on the form it is in. King's Shield is lethal to physical attackers, and Swords Dance can be lethal to everyone. Ghost + Fighting attacks has very good coverage with each other, as well.
Mega-Banette: Gengar was not the only Ghost type to be graced with an megalution. While regular Banette is OK, he isn't someone I would go out of my way to use. However, as a Mega he get the awesome Pranskter ability, as well has very high Attack. This means he can have priority Will-o-Wisp or Toxic and then hit extremely hard with Shadow Claw or another attack. Definitely a pain to face.
Alright, so I don't give you a definite answer for a good Ghost type, but that was never my aim. Since I don know anything else about your team, or even whether you mean competitively or in-game, I don't have enough information to give you a definite answer. Instead, just read the brief description I have given for each one to get an idea of their potential strengths, and decide for yourself which is best. Whether you are after a wall like Cofagrigus, a Special Attacker like Chandelure, or an annoyer like Sablye is completely up to you, and each have their uses.
Honourable mentions: I nearly listed every fully-evolved Ghost type. But here are the ones I didn't mention at all:
Shedinja - while it can potentially stall out entire teams, it is taken out so easily it will probably be dead weight more than anything else
Drifblim - decent enough Pokemon, but I don't think it is on the same calibre as those I mentioned
Froslass - I like this one, but it is really best used as a suicide lead/spikes setter, and that doesn't really appeal to many people, as it is very predictable
Giratina - It's a legendary so I didn't include it. End of story.
Gourgeist (Gen VI only) - I really don't like this Pokemon, but there is no real reason why, althoguh its stats certainly leave much to be desired.
I hope this was useful (to some extent).
