I used borowlens.com for several lens rentals over the year. Everything arrived when promised; the gear was in tip-top shape; and their prices are reasonable when compared to other on-line companies and cheaper than my local Penn camera store. I would highly recommend them.
I first heard of borrowlenses when I needed a canon 24-70 lens in a pinch before a wedding shoot as my broke. Their prices are great for rentals when you need the extra gear at the last minute. I also have used them to rent out an extra body for shoots where I need an additional camera. Their prices are very reasonable. For a 5Dmiii it comes to a 35 dollars per day. Pocket change when to buy a new one it costs $3400. Shipping back and forth is seamless and I did a local pick up and drop off once and that worked out well too.