@Brandon Turner So it seems that the cover of the book has some weight on the outcome after all... :-)Kudos,Mary

Faster and cheaper. 

we allow pets, just not 8 breeds, which is set by the insurance.we charge $25 extra per pet per month in addition to 250 cleaning fee.some dont charge anything, but those are desperate landlords, with crappy units.it seems to me that all tenants have to have pets. they can't afford their own housing, so they go ahead and make it harder on themselves by adding more weight on their shoulders - higher rent and pet bills. makes perfect sense to me!

Also using a partner who wants to match your portion in turning units at a faster pace to fill units. 

Option 3 would be faster. 

The only difference that I could suggest is possibly using HML or peer to peer loans for the purchase and then refinancing into a long term conventional loan if you want to grow faster.

The tax advantages are heavily weighted to ownership and residence in a primary residence.  

As you have more loans banks don't want to loan to you so you have to find other financing. but if you move to apartments it is easier and faster to acquire one loan for 25 units than 25 loans for 25 houses.

IMO if you find a good agent, he will be worth his weight in gold.

Wholesaling and flipping give you the most liquid asset ($$$) but nothing else whereas the other strategies mentionned give you long term investment vehicles that will hold value and appreciate at the same speed or faster than inflation and will give you a cash flow while doing so.