[guesswho]

electrician here.
Colour is personal preference, 2700-3000k gives you a warm home feel (think incandescent old school bulbs) whereas anything over 3000k gives off a morgue kind of feel imo.
Costco bulbs seem to do fine from my experiences, have done plenty of homes where customers have chosen to use costco bulbs with little to no complaints
You can always buy the costco bulbs and return them with the return policy if you dont like them