First 4plex purchased and a god-given 500k cash to invest!

[Maxim Ouellet]

I just purchased my first 4plex in Trois-Rivières(Quebec,Canada) I paid 206 000$ at a  2.04% with rbc. I have put 20% down(42 000) the place cashflows 580$ a month. extremely grateful for that.

As if this wasn't enough, yesterday we had the amazing news that a wealthy family member is ready to pay cash for a property up to 500k for us(Plex, house, etc) to live in and  repay him monthly interest free (about 1 500$). 

knowing that a part of the loan could be used for renovation, what would do you think would be the best investment for us when taking into account comfort(as we would live there) and rentability) ?