Like others have said, the more the merrier. Max out the bonuses and enjoy any promos. Otherwise, just line shop as usual.
I live in a state where it is legal and have money in FD and rarely use it, still use offshore. It's been weeks (and I place 15 bets a day) since I've found a better number on a game there (I check FD about 75% of the time, not every time mind you). Using rough math as a $200 game bettor, if I bet all of May's plays at FD instead of offshore, I estimate it would have cost me over $2,000 to do so.