I am looking for an open source LMS, so Totara or moodle which is better?
The answer for this question of choosing between Totara and Moodle really comes down to your needs and budget. What features do you need, and how much are you willing to invest in ensuring your employees or students have access to the necessary training and resources? It is hugely important to be aware of the work involved with turning Moodle into a workable LMS, let alone one that is customized to your needs and matched to your branding and identity. Are you an educational institution or an organization? Moodle was designed not for enterprise, but so that educators could have access to a platform that allowed them to track and monitor learning within their own institutions. Totara, on the other hand, is a heavily customized and enterprise-ready LMS which caters specifically for the needs of businesses rather than education.
You can also consider this comparison chart for great help: