I am at lvl 20 base which class is best to reach lv22 fast with out spending money?

Upgrading your base (and buildings) required rss. Use whichever class will let you earn these the quickest. The farmer has the best idle production rate if you are not able to play frequently during the day or are not in a position to attack a lot of other players. If you are able to attack players regularly (ie there is no restrictive NAP and you have plenty of time) then the raider class can let you earn more if you choose your targets well.

Having farm accounts set up will also let you make regular safe attacks from either of the above classes.

I am told raider is good for people over base 20