Hiya!
Well, other than "custom home made"... I'm going with Hackmaster 4th Edition. Has
ALMOST absolutely everything I use as a GM during a game session, immediately before a game session, or right after a game session. The only think I wish it had that it doesn't is the tables for "Horse Traits and Markings". Yes...I use that a lot; anytime a horse becomes "important" to a situation...which is, surprisingly, quite often! I mean, the PC just bought a horse and is riding out of town when he is surrounded by a pack of hungry street dogs, all barking and nipping.... yup, I need to know how this horse reacts. The PC decides to go shopping for a new horse... definitely need them then! PC sneaks over to steal a horse from a camp of bandits nearby? Yup...I need that info!
But other than the horse thing... the HM4 GM Screen is AMAZING!
^_^
Paul L. Ming