$150k available to invest. Multifamily or an apartment building?

[Matthew Berry]

My wife and I did a "house hack" several years ago. We bought a foreclosure from HUD for $56k in cash, fixed it up, and now it's worth $160k. Recently we moved into a bigger house (four kids now) and changed it into a rental. It currently cashflows for $1,000/mo (after expenses, $1350/mo rent). We're ready for the next step!

I watched @Brandon Turner's amazing webinar last week on buying your next rental property in 90 days. We watched the webinar. We bought his book. 

We want to shoot for Brandon's plan of $1,000,000 in 7 years. Since we already have about $150,000 in equity right now, it seems we're somewhere around Year 3 in his plan. At this point, I'm not sure of which path to take. I basically see two options:

Option 1: Fourplex Multifamilies

• Refinance current rental, pull out $120k
• Purchase three fourplexes with a $30k downpayment
• Now have 12 units cash-flowing $200/mo/unit
• $2400 per month (not including rent from our current rental)

Option 2: Smaller Apartment Building

• Refinance (or sell) current rental
• Purchase smaller apartment building for $750,000
• Now have 8-12 units cash-flowing $200/mo/unit
• $1600-2400 per month

Any insights you guys may be able to provide? 

I'm specifically looking for:

• What am I not thinking about?
• Does one option carry more risk than the other?
• What mistakes have you guys made that I can learn from?