@Sam Stoffels in our current twin cities market I think duplexes and townhouses are tough to find; and both are GREAT strategies for a newbie.
Regarding townhouses, there are a few downsides. HOA costs will cut significantly into your cashflow and associations can impose all sorts of rules and fees to restrict the number of rentals. If you owner occupy for a year with intention of making it a rental later, you could get caught in a rule change.
On the other hand you don't have to hire out snow clearing or lawn cutting, and don't really have to budget for exterior maintenance long term.
Duplexes in the area are often older buildings and may have deferred maintenance. Cash flow or rate of return should be much higher with a duplex but I would estimate much higher capital costs long term.
Side note:
If you plan to owner occupy for one year you have a great advantage over other investors. You can buy HUD and Homepath homes that need a bit of work and you can bid on them two weeks before other investors. You should be able to get a good discount, and you might not need to put 20% down.
I also believe now is a great time to lock in great interest rates and its only going to get a lot more expensive to get financing later.
So, consider looking for a HUD or Homepath that needs cosmetic updates; get in with a low downpayment 3.5%-5% and use your extra cash to fix it up. Live in the house for one year. If rates are still low, refinance to get most or all of your money back out. Rent it out and go buy another place to live in.
When you do the numbers on these deals make sure you would make some cash flow on it once fully rented and refinanced one year from now. Good Luck