Hi Nick,
Quality 12–14 oz belt blanks are a great choice for durable belts — that weight hits the sweet spot between strength and flexibility for everyday carry. Herman Oak is definitely one of the go-to options, but there are a few other U.S. vendors and leathers worth considering:
• Wicket & Craig — similar veg-tanned weight, excellent for belts and heavy leather projects.
• Schneider’s Veg-Tan — reliable 12–14 oz veg tan with consistent thickness and great tooling surface.
• Tandy’s 12–14 oz veg tan can work well for belts if you’re okay with a slightly softer feel to start with.
A quick tip when sourcing blanks is to check whether the hide is from the shoulder/neck area versus the belly — shoulder cuts tend to be tighter and stronger, which is ideal for belts. Also, getting them from U.S. suppliers usually keeps out nasty shipping surprises and supports faster restocking if you work through blanks regularly.
What will you be using the belts for (E-DC, western carry, dress)? That can help fine-tune the leather choice.