IRA options for self employed : Solo 401k vs SEP IRA

I need advice on tax structure that would allow me to contribute to pre tax IRA account.   I have 2 sources of income. 

 

1) Capital Gains from real estate and trading

2) Consulting Business where I'm the sole proprietor and don't expect to have any other employees in forseable future.  Expected income in low 6 figures for current year. Not registered as a separate entity or have a unique tax id.   I'm making estimated quarterly tax payments. 

 

I can comfortably sustain my living expenses from #1.  The goal is to put as much income from the consulting business (#2 above) into IRA to lower taxable income.  As I understand, I can set up a SEP IRA or Solo 401k. 

 

Given my situation, which of the two IRA accounts is more suitable?  Does one have higher contribution limits than other? My preference is keep things as simple as possible so would like to avoid setting up an S Corp, report as employee and deal with payroll etc.