Top limb

[DC]

How do you decide which is going to be the top limb? All reasons, tiller, aesthetics, anything.

[MWirwicki]

For me:

First: Which side of the bow's centerline that the braced string favors from should determine which limb should be on top.  Less "Archer's Paradox".
Second:  If dead center, then the weaker limb on top (provided the bow is symmetrical).

[PEARL DRUMS]

Same as Matt. If I have control over limb length and alignment I will put the limb with the most character on top for my eyes to see.

[Pat B]

Like both above.
 I make my bows symmetrical. I'll shoot one in sometimes before determining top limb but not always.

[JW_Halverson]

As I lay out a bow, I will incorporate the end of the stage with the most character into the upper limb.  No reason other than it draws more attention.

[wizardgoat]

Most my bows I make my top limb longer, and like pearly and JW, I always put the limb with more wiggle and character on the top

[Jonas]

I do not build my bows symetrical. For me, the most crucial factors are:
1) If there are potentially weak/problematic spots I try to put these in the upper limp. The lower limp has to bend more, weak spots are more stressed (if you let them bend)
2) If there is a reflex, I try to to put it in the lower limp, so it becomes faster. I put a deflex in the upper limp.
3) I ask myself which choice of limps favors the string (as MWirwicki said, less Archers Paradox)
4) aesthetics

[mullet]

I do like the above except put the crooked limb on the bottom for less distraction, unless it has a hole it.

[SLIMBOB]

Usually the most character on top. 

[Dances with squirrels]

I put the limb with the most imperfections(not necessarily character) up top. My bows are asymmetrical.

[Del the cat]

All the above
Del

[Pappy]

Same as Matt.
 Pappy

[BowEd]

About the same as everyone but I put the more reflexed limb on top.It ends up with more material removed and needs to bend more and over time I need the bottom limb to stay stronger.That's my reasoning and over many bows has proven to work for me for durability and efficiency over time.I've done it both ways.That's with even lengthed limbs also.
As far as string alignment on handle I remember where the string lays at low brace/grab the handle and look and feel it to determine that way too.I shoot it too lots of times but most times I can tell just from handling the bow at brace and looking at string on handle.

[BowEd]

DC....Also my handle centers are 1.5 to 1.75 below arrow pass too.

[Joec123able]

I sight down the stave and look which side the string will track down. Which ever side determines what limbs are what.