48v electric forklift battery charger with 240v power source?
Without knowing the details of either charger, I can't make any real recommendation, but I wouldn't buy Expert B's charger since he says it is not suitable.

Howver, the charger you select should be "smart", and provide a "three stage" charging profile - bulk, absorbtion and float.  Such a charger will not over-charge the battery, and should have a charge current capability suitable for the rating of the battery it will charge.