Tuning Which is better? Desiccant or cotton filter

Any filter you put in the output line will be exponentially better than something on the input line which will do very little no matter what it is. Hand pumps are rough to filter as every little bit of volume you use for a filter means bunches of extra pumping. 

Think seriously about a Yong Heng compressor they are inexpensive, werq very well and are probly the best out there for under $1000 yet they are just over $300.