My favorites are still Wizard and Cleric, but I have been noticing more and more that I am not having fun because I am not hitting anything. I am currently playing a "Shielding Cleric" in a campaign. With a +6 to hit at level 2, I can't hit the broad side of a barn.
A +6 at 2nd level should be fine, unless your DM is using overleveled monsters a lot. One of the tricks to playing a 4e implement user well is targetting the 'right' (ie lowest) defense. It's not always easy, but you can often guess from a monster's description or actions what it's defenses might be like or what role it might be, and from role, you can guess at low defesnse: Brutes tend to hit hard, if not often, and generally to be big and straightforwards - they tend to have very high FORT, so WILL & REF are your best bets. Controllers tend to be good with all defenses, but REF is sometimes the low one. Skirmishers and Artillery tend to lack FORT. Actually, WILL is rarely ever high, with Controllers being the most likely exception.
As the encounter progresses, you can further feel out defenses and vulnerabilities and choose which attacks to use to best effect.
Of course, there are also options to just pump your attack bonus. A high primary stat and magic implement are the obvious ones. With a Wizard, you don't have a strong need for your secondary stat, so a 20 isn't out of the question. A 16 probably should be out of the question. With a Cleric, you might want some STR or CHA or CON, depending on your build, so might settle for a 16, especially if you're not a +WIS race, or an 18 if your do have +WIS. You can also take an Implement Expertise and/or proficiency in a Superior 'Accurate' Implement. There are a (very) few other attack bonus feats that'll stack with Expertise.... (Hellfire Blood is the only one I can think of off-hand).
There are also situational ways to hit more often. Combat Advantage is the most obvious, but not as easy for implement types to get (wizards aren't known for being stealthy). But, Distant Advantage (feat) is an option. If you're using Fortune Cards, salting your deck with Phanton Ally does the trick. Leaders can hand out attack bonuses. As a controller, you should be able to inflict the occassional defense penalty or combat-advantage-granting condition, like Daze. Also, while you don't get CA as easily, Area and Close attacks ignore concealment (and can get around cover, sometimes), and of course, traget multiple enemies (meaning you're more likely to hit at least once), so theyt can also help you hit more often, relatively speaking.
Finally, if you're a Mage - or just choose Magic Missle - you can always fall back on that when an enemy proves hard to hit, or you feel your dice are 'cold.'
