Free and every feature I'd need, there are a lot of features I haven't even used.

I'm a Graphic Designer from Sydney, Australia living in Brooklyn, NY.

I like the search features: https://www.biggerpockets.com/search

Several updates and custom design elements.

What I like about TenantCloud over something like Cozy.co is that it has automated template leases / notices, electronic signatures, an accounting feature, robust mobile app, and great reporting features.

Hey guys, what do you guys suggest as the best design staple to go with for a house flip?

When you buy property that is well located in a market with diverse economic base, that is growing, that has many attractive features, and is reasonably priced compared to the average income for the area, you set yourself up for success. 

As an architect I have studied them and have seen various projects designed and built with them.

Put all the features of this house(bedrooms, # of garages, bathrooms, basement-finished, basement - unfinished, Central HVAC, Updated, Not updated, High-end features, Middle-grade features, low-end features, etc).  

They have plenty of free trainings, through their tutorials on how to best use their features.