I've had issues with both. Our local HD has some rude assclowns working there, and Lowes people are more helpful and nicer. Lowes has nicer stuff in the store, but HD lumber is better and having ordered stuff from both, HD is heads over Lowes in that department.
These are just two examples...
Ordered a patio door from Lowes. The installer measured it before it was ordered, but they didn't use his measurements, instead they ordered using my rough measurements. The installer was beside himself but it was usable with a little work, shimming the top and sides and all would be covered by the trim. Lowes wanted more money to do this! So to fix their mistake, I would have to pony up another $175! That went over like a fart in church and I set the phone lines on fire to the local Lowes. They weren't backing down at first, but once they realized they would be taking back a special order $1700 patio door, they backed off. Installer was great though.
Ordered new garage doors from HD. They came out, double checked measurements, ordered and installed doors. End of story.