I get this question a lot...  I believe the difficulty level changes depending on how often lock was used, weather and how old it is.  In a perfect scenario with a perfect lock....Picking I would put HU64 as the most difficult for most people.  The issue is not the lock but the length and thickness of the lishi tool levers.  This throws people off as a stiff wafer might feel like it's got some spring to it.  So this lock I teach people a slightly different technique in order to not be fooled.  Easiest lock to pick and decode?  CY24!!!

Should I lishi or not?  Most door locks do not have all the wafers.  Most are missing one or two....european brands usually have all.
If you are missing one, two or even three wafers its ok to lishi.  If you are dealing with a GM made car from about 01 and older that only has about four wafers out of ten in the door...do NOT waste your time using lishi.  It will give you several hundred keys.

Prices of key codes keep going up.  Why do people tend to order codes from a "code" distributor instead from the manufacturer?  The answer is simple, most require LSID.  Majority of locksmith are not part of that group.  I also know many who are part of LSID but do not want to order codes as it requires filling up paperwork and getting a lot of info from customer....headache!!

I have trained many who have failed teaching themselves.  Once I look at their technique...all have the same issue.  Too much tension!!  I teach them a method in which it allows to feel how much tension is required for the particular lock.  The lightest tension is usually on locks the use skinny high security keys like HU100, HU101 and HU64.