I use ascending AC in my campaign and find it much faster. d20 + Fighting Ability (or hit dice for monsters) + attribute bonus + magic bonus >= AC is a hit. Much easier for me to DM and for new players to learn. To compute ascending AC, I subtract descending AC from 20.
This is what I use. My group is almost exclusively 3e era friendly and on newer players. While I prefer to allure and nostalgia of descending AC, it's a minor concession for me to use Ascending AC to get them to try a game like this.