Closing Recommendation
Both machines are strong choices in the same class, so pick by how many hours you really run and what service you can reach. Choose the CAT 320D3 when your machine works long continuous hours on mining, highway or large project work, you want a build that survives years of that, and you have a workshop close enough to keep it going. Choose the Hyundai R210 SMART X Plus when your work varies through the year, you want more power and a choice of bucket sizes to match different material, and you want a lower cost to buy with service that reaches into smaller districts. Compare both over five years, not on the invoice. So match the machine to your work: CAT 320D3 for heavy continuous hours, R210 SMART X Plus for varied work at lower cost.