I have used only used quest helper and cartegrapher for a while now and am not really satisfied with it. When grouped with another it doesnt always (rarely) show what and where their objectives are. I recently grouped with someone that had another questing "aid" addon and i was surprised that their addon was more informative than QH. I wish i remembered the name they told me it was. 

My question is:  Can you please recommend what you think the very best questing/Leveling aid out there is?  Thank you for the help

The major competitor for QuestHelper is Carbonite, which is a lot more than just a quest aid. You can check it out on wowinterface.com

Lightheaded will add comments from WoWhead DB into your questlog. Used with QH, i imagine you'd find the two to be pretty comprehensive.

http://www.wowinterface.com/downloads/info7017-LightHeaded.html

If you're looking for a few things to help with grp questing, try Quest Mods (helps you track your party member's quest progress) and Follow Felankor (helps your party member to put you on auto-follow if you happen to go AFK for a couple min).

http://www.wowinterface.com/downloads/info11821-QuestMods.html

http://www.wowinterface.com/downloads/info7171-FollowFelankor.html

I switched from QH to Zygor's Guide. It's not free but they just released a new version which is awesome and I have been leveling like a madman. My Human Warlock has gone from level 20 to 63 in about 2 weeks of normal play. The interface tells you exactly where to go, how to get there and what to do with a few useful hints thrown in.  It costs $50 for either Hord or Alliance or $90 for both with some extras thrown in.

I have tried a few of quest mods, and for me I found the best to be a combination of Carbonite and Lightheaded.  Quest Helper is good, but it really uses a lot of system resources that Carbonite does not seem to.  Lightheaded, well ... that is simply notes from players that have done the quests, which more times than not, you will find the advice easier to follow and more accurate.  If there are any bugs affecting a quest, lightheaded is great for that as well.

The very very best mod though ... it one you try and like the most. :)