I've never heard it said that pine straw repels any sort of insects. One problem with pine straw (I'm in fire ant country) is that fire ants and other ants seem drawn to it, so if ants are an issue for you, you might choose to avoid the pine straw.

Generally, cedar mulch, if it is freshly ground and still highly aromatic, has some insect-repelling qualities but I think even that is overstated. On our property, the cedar trees we have not yet cut down (having already removed all of them in the area near the house) are tick magnets. If you walk under or by one of those cedars during tick season, the ticks will jump from the cedar tree to you. So, if cedars really repel pests, the ticks didn't get the memo.

My vote would be for the use of ground oak leaves. One of the fascinating thing about oak leaves is that they contain a lot of nutrition, including micronutrients, and they contain them in roughly the proportions needed by plants. Many of us use copious amounts of leaf mulch every year. I've used it for 13 years now and my garden soil where it is used has turned from brick-hard red clay to loamy-clayey brown soil. As a bonus, earthworms love leaf mulch and it attracts them to the areas where it is used.

I think all mulches enable squash bugs to hide. What I do is put a board on the ground very close to the squash plants. The squash bugs retreat underneath that board during the heat of the day and sometimes at night. All I have to do is lift the board to find the bugs and then it is easy to kill them quickly before they run and hide.

Straw often does seem to give pests a place to hide, so when I use spoiled hay or straw, I mix it with my chopped and shredded leaves and also with grass clippings. If you are bringing in straw from an outside source, you have no way of knowing if it really is 'clean' or if it is contaminated with herbicide residue which is a huge issue nowadays. I don't use any straw or hay without testing it for herbicide residue because of all the issues with contaminated compost, manure and mulch killing gardens nowadays. The testing is annoying and slows me down a lot, but it is less annoying than having the entire garden die. Alfalfa is the exception, being a legume instead of a grass so it cannot be treated with the persistent herbicides for grasses which are causing the contamination issues.

I think the best mulches are whichever ones are most easily obtained locally. I tend to go strictly with mulching materials from our own property as much as possible because I know none of them have been chemically treated. However, we have several acres, some of which are heavily wooded, so that gives me "enough" mulching material. On an average city lot a person likely would not have enough naturally-occuring materials available to fill all their mulching needs.

This year, I was the very grateful recipient of 197 bales of hay from the last cutting of 2010. It was raised on property that borders our back (west) property line. I'll be able to use that hay once my contamination tests are complete. However, I'll still mix it with fresh grass clippings and chopped/shredded leaves because I like having a variety of mulching materials. When you have a variety, it just better enriches the soil as it decomposes.