Practice - whatever works best in your gun and won't break the bank. WWB's are good, but there are others.
Be prepared to hear some outlandish reasons for why people carry certain SD rounds. Do your own research and look for unbiased results. There are a lot of LE Departmental test is you search for them.
There is a lot of ignorance out there in Internet land.
After reading many honest and unbiased ballistic tests and putting various rounds through my own gun I have settled on Federal HST's. I prefer the 147grs.
Your milage may vary.