Mike Mearls did an AMA, as part of it he revealed he likes doing his own homebrew initiative system. It sounds really complicated.
http://www.enworld.org/forum/content.php?4119-Here-s-Mike-Mearls-New-D-D-5E-Initiative-System
It's like, declare your action first, and depending on the type of action, roll different and/or more dice.
Shoot an arrow? Go first.
Swap staff for wand, move to good vantage point, and cast Fireball? Go last.
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Myself, my take from that was it's okay to decouple Dexterity modifier from initiative. I think next game I run I want to use Savage Worlds style dealing playing cards.
Deal out playing cards to players and one for each NPC or group, then count down in descending order, collecting cards as they act. Sooo easy to tell if someone hasn't acted yet or where we are in initiative order if I get distracted.