One good reason to prefer increment over delay, at least in the USA, is the way delay is implemented on the most popular clocks.
The Chronos does everything well, but I’ve been hearing (on other threads) that that clock may be near extinction, with prices up to $300, etc.
Its likely replacement will be the DGT North American, which in my opinion is the best affordable clock currently available. But it has a crummy way of displaying delay. The word “delay” (in tiny print) is displayed for 5 seconds, before the main time starts counting down. You have no way, to know, at a glance, how far into your 5-second delay you are.
The Saitek is perfectly horrible in this regard, as well. It displays the delay seconds instead of the main time, in the very same area of the display normally used for the main time. That can be extremely confusing in time pressure.
The Excalibur Game Time does delay quite well, but I keep hearing rumors of that clock’s demise, as well.
On top of all this, there is ongoing disagreement as to the best method of displaying the delay. Should it be done as “straight” delay, or as non-cumulative addback (Bronstein style)? They are mathematically equivalent, but players have strong preferences one way or the other. Some like “straight” delay so that they can use 4.9 seconds on each move, to optimize the efficiency of their time usage. Others prefer Bronstein because a single display always tells you exactly how much time you have remaining. Ironically, proponents of “straight” delay are thwarted by clocks like the DGT North American, which never tell you how many delay seconds you have remaining.
Because of all this, and for other reasons, I tend to prefer increment over delay. For Blitz this preference is strong, with G/3 inc/2 being my favorite. For quick- or regular-rated events, if the delay or increment is 5 seconds, it doesn’t make a whole lot of difference. With 30 seconds, you’re into more leisurely time controls, for which increment seems better suited than delay.
Bill Smythe