Best table name instead of "user", if the DB doesn't like that

Put some context in the name. If the table is for a CMS, maybe name the table CMS_USER. If it's a reporting tool, REPORT_USER. You could include the application name in it, as ${applicationName}_USER. Failing those, would just APPLICATION_USER be OK? I did once see a table named UZER, along the tradition of naming a variable representing a class as clazz, but I'm not too fond of that one. You could do something like U5ER, since a "5" sort of looks like an "S". Or you could just go totally phonetic and name the table something like YOOZER.

For table names, you can prefix your tables with t, tbl, etc.

CREATE TABLE schema.tuser

Personally, I like to make my tables plural, as if it's a table of users, rather than a table of user.

CREATE TABLE schema.users

If you don't like either of those options, you can always be more descriptive when making your tables. What kind of users are they? What is the database for?

CREATE TABLE schema.appusers