Compare what you actually use
A lower recharge price does not necessarily mean a lower cost over the same period. Divide a fixed-validity plan’s price by its number of days to compare the daily cost.
Then consider data allowance, local coverage and the subscriptions you actually use. A calendar-month plan is different from a 28-day plan: the number of days in each billing period can vary.
Use PlanHub’s comparison tool as a starting point, and check the operator’s final terms before buying.