We've use Easypopulate CSV on our 1.3.9h carts and it works well. But since zencart 1.5.x I've used Easypopulate 4 and like it better.

I took a brief look at easypopulate excel and knew I would not likely use it...but do not recall why.

BTW, we've used Openoffice and Excel on both Easypopulates.