I love to use pine needles - they don't tend to clump and they last a couple years. Maybe due to the slow decomp, I have not had any pH problems.

I can’t imagine gardening without straw bales as a mulch basis. I keep one bale in each of three garden areas and keep adding straw to beds as the older straw decomposes. Worms do love it as many have pointed out. I also grow 95% of my tomatoes in straw bales. After two years each bale has decomposed to almost being soil and is a great addition to my flower beds as well. In some beds I have also started putting down straw and manure first with wood chips on top. It’s all good and helps cut down on the weeding.