What is the best and cheapest data sim only in the...

Best overall cheap pick for a phone: Youfone 30 GB SIM-only — about €5.08/month effective average on a 2-year deal, KPN network, 5G, 200 Mbps, with 300 min/SMS. It is not the absolute lowest monthly effective price, but it gives the best balance of data, price, and network quality among the cheap deals I found. (Mobiel)

Absolute cheapest effective phone SIM-only deal: Ben 20 GB — about €3.83/month effective average, 2-year contract, Odido 5G, 200 Mbps, 200 min/SMS, but the effective price depends on cashback. (Mobiel)

If you literally mean “data-only SIM” for a tablet/laptop: the cheapest listed deal I found is Odido Data Only 2 GB for €5/month, 2-year contract, 300 Mbps 5G. Note: a Dutch data-only SIM usually gets a 097 number, not a normal 06 phone number. (Mobiel)

Best quality/service pick: Simyo, especially if you value reliability and customer service over the absolute lowest price. Consumentenbond named Simyo “Beste uit de Test” with an 8.4 in Q4 2025 and a 9.8 satisfaction score. Current cheap deal: 20 GB for about €5.83/month effective average on KPN 5G. (Consumentenbond) (Mobiel)

My recommendation: get Youfone 30 GB if you want the best cheap all-round phone SIM. Choose Ben 20 GB only if you mainly want the lowest effective price and are fine with cashback/2-year terms. Choose Odido Data Only 2 GB only for a tablet/laptop or hotspot device, not as your main phone SIM.