For routing-heavy labs with limited RAM, IOU L3 is unbeatable. For official support or hybrid L2/L3 switching, CML or vIOS may be better.
Do you still use IOU in your labs? Or have you switched entirely to EVE-NG? Let me know in the comments below! Cisco IOU L3 - GNS3
If you are studying for the and focusing on advanced routing (OSPF, EIGRP, BGP) or MPLS , IOU L3 on GNS3 is still the gold standard for performance. For routing-heavy labs with limited RAM, IOU L3