Foster retired from international football 18 months ago and has refused to budge from that stance. But the former Manchester United player has maintained his high standards and produced another superb display in Sunday's 1-1 draw at Aston Villa in front of England manager Roy Hodgson.
Long, who scored the opening goal at Villa Park, said: "Ben is a brilliant keeper. He shows it in training sessions and you can see it every game on the pitch."
Asked if Foster is as good as Manchester City and England number one Hart, Long replied: "I think so. I've never trained with Joe Hart but you see it every day in training, the saves Ben comes out with.
"He is one of the best keepers in England and it is a big loss to England not to have him in the ranks, but they are lucky to have Hart who is there to do a job. You will have to ask Ben what his reasons are (for not playing for England) but it is working well for him in our team. England's loss is our gain."
The Republic of Ireland international said: "He has brought his own stamp on our football. Straight from the start it was all about passing football, and how he wants us to play. When he has an idea, he is able to put it across really well to the players."
Albion have collected 11 points from their opening six games to lie sixth in the Barclays Premier League.
Long, whose goal was cancelled out by Darren Bent's equaliser, said: "It shows how far we have come as a team, to come to Villa Park in a big derby and leave disappointed with one point.
"It's good for us as a team to expect more from ourselves. If we put in performances like that for the rest of the season, we will go very far."