Investing for 1099 employee

I just started to work as a 1099 employee and started an S-corp. I and am trying to determine if I should max out an owner-K then use profit sharing to invest the max $52K per year or if I should do a SEP IRA with the max $52k contribution. I was told that if I go owner-K I can still contribute my annual $5500 to a traditional IRA and convert to roth which I have been doing for years. If I do the SEP IRA I would not be able to do this.

Just curious how other 1099 employees handle their investing. Any help, tips are much appreciated.