What about the environment you drive in and its effect on how long anything lasts in the fenderwells ?
If you live in sunny, dry areas, well then armorall would last a long time, compared to living where it rains a lot and there is lots of dirt on the road that gets splashed up into these areas...
In absolute perfect weather conditions, Meguiars Hyper Dressing works great, is so easy to use, smells awesome, but even there, it doesn`t last very long..
So, if you are ok with spraying it - and that is all you have to do after cleaning those areas, then its a great looking choice...
The other more oily sprays, Bare Bones, Griot`s, work great without a lot of pre-work and last a little longer in bad weather, but eventually, they wash off too..
Their advantage, in my experiences is they are fast, smell great, and leave the fenderwells dark, which matches the tires when light gets up in there when the car is in the sun...
The only one we haven`t discussed yet - Chemical Guys, Back to Black Spray Can...
Pros - Clean the area, when dry, spray the area, walk away...
Leaves a very nice, black finish, that dries kind of like a wax, will last pretty long depending on how much water gets blown up there driving, ease of application..
Absolutely turns any engine compartment beautifully black, and not greasy, smells great...Lasts awhile until the extreme heat under there takes it out...
Cons - Not the cheapest - but its in a tall spray can, so how much is the convenience worth to you?
Dan F