Help with choosing conventional vs USDA Loan

[Kyle Na]

Hello all,

I am completely new to the game and really need some advice about financing my first upcoming house purchase. Due to the generosity of a family member and some good timing, I am in line to purchase a new house somewhere around 245-260k in a market where it will value near 380k-410k. The house will be a new build, 2150 sq ft 5 br house. I have two financing options:
Conventional loan - from what I understand, it may be possible for me to use some of the equity in the house as a down payment. I need to speak more to my relative about this, but I believe it would along the same vein as a construction loan turning into a conventional mortgage with the equity being the downpayment. 

USDA loan - As it stands, I qualify for a USDA loan on the house. I have a meeting with a bank soon to learn more about the process. From the calculations that I have run, it looks like the mortgage will be around $1300 + the mortgage insurance (~$75 /mo). We plan on moving in the house, and I'd like to grow a portfolio with the equity that we will have. Would a USDA loan be better for this since I wouldn't be using the equity as the downpayment, thus making it available for a HELOC? I'd like to use the equity in the home for an investment property, so am hesitant to go the conventional route even if it saves me 75 bucks a month by not having to pay the quasi pmi. Am I overlooking anything if I do the USDA route?