Because of
this thread (which you should read, it's good stuff!), I took a look at some of the variant rules in the DMG (also a must-read).
Anyway, I haven't tinkered with Initiative variants very much. While the RAW system isn't perfect, I also haven't seen any variant system that offers enough to warrant replacing RAW.
That said, I'm slightly curious about the Initiative Score variant in the DMG, In a nutshell, everyone gets a flat Initiative score equal to 10 + Dex (so basically a passive Dex score). Combatants then act in order of their score.
Pros
Less die rolling, which speeds up combat.
Rewards characters that have invested in Dex and Initiative.
Predictability allows the party to tailor strategy.
Cons
Less die rolling. Rolling dice is fun.
Penalizes characters with low Init scores. They never get a chance to act higher in the order.
Has anyone tried this? I'm inclined to give it a try. The pros outweigh the cons for me. While it's a bummer that slow characters will always act later in order, it is frustrating to have a character with high Init be penalized by poor rolls. Plus determining order at the start of combat can be time-consuming.
With this method, I'd also think about trying Init = 10 + Dex + Int...maybe (with ties going to higher Dex).