Short answer: there’s no single “best” nationwide — but these insurers are consistently rated best for truck/commercial-vehicle claims service and are worth checking first:

• Progressive Commercial — large national carrier with a dedicated heavy‑truck claims organization, in‑house adjusters, 24/7 claim reporting and a nationwide repair‑shop network to get trucks back on the road quickly. (progressivecommercial.com, fitsmallbusiness.com)
• National Independent Truckers Insurance Company (NITIC) — small specialty carrier frequently singled out for fast, owner‑operator‑friendly claims service and strong customer reviews. Good pick for owner‑operators/small fleets. (constructioncoverage.com, nerdwallet.com)
• Sentry / Continental Western / Canal (specialty truck carriers) — regional/specialist truck insurers that use experienced in‑house adjusters and tend to have low complaint rates for commercial truck claims. Good for fleets that need trucking expertise. (dat.com, bulkloads.com)
• The Hartford — often recommended for tow/specialty trucks; known for 24/7 claims support and solid commercial claims processes. (fitsmallbusiness.com)
• 1st Guard / Acuity / Great West (Old Republic group) — smaller or trucking‑focused carriers that show strong customer satisfaction, low complaint indexes, and strong financial ratings (useful for claim‑paying ability). (dat.com, constructioncoverage.com)

Why you’ll see different answers

• “Best” depends on your situation: owner‑operator vs large fleet, local/state availability, cargo/hazmat exposures, and whether you need quick physical‑damage repairs or complex liability claim handling. National consumer studies and regional specialty carriers both matter. For example, J.D. Power’s small‑commercial studies highlight large national brands (Nationwide, State Farm, etc.) for overall small commercial satisfaction, while trucking‑specific reviews favor specialty carriers for hands‑on truck claims service. (jdpower.com, businesswire.com)

How to pick the best for your truck(s) — ask every prospective carrier/agent:

• Do you use in‑house truck‑specialist adjusters or third‑party/independent adjusters? (in‑house = usually faster/more consistent). (progressivecommercial.com)
• Do you offer 24/7 claims reporting and a dedicated single point of contact for truck claims? (reduces downtime). (progressivecommercial.com)
• Do you maintain a truck repair network and a repair‑management process (guarantees, timelines)? (progressivecommercial.com)
• What are your average time‑to‑settle and average cycle times for heavy‑truck physical damage claims?
• Can you give references from other carriers/operators in my state or with similar equipment?
• What is your AM Best (or S&P/Moodys) financial strength rating and NAIC complaint index? (use these to verify claims‑paying ability and complaint history). (investopedia.com, constructioncoverage.com)

Quick resources to verify and compare

• J.D. Power (small commercial and auto claims satisfaction studies) for customer‑experience rankings. (jdpower.com, businesswire.com)
• NAIC complaint index (compare complaints relative to market share). (investopedia.com)
• AM Best / S&P ratings pages for claim‑paying ability (look up each carrier). (constructioncoverage.com)

If you want, I can:

• Narrow this to your state and truck type (owner‑operator, long‑haul, local box trucks, tow trucks, hazmat) and give the top 2–3 carriers to request quotes from, or
• Pull the NAIC complaint index and AM Best rating for any specific carriers you name.

Which would you like me to do next?