Ability to stack on pre-existing stacks might not be as good as it sounds. You have a very high risk of knocking over the initial stack. It’s probably best to just make a really high capacity tray and not bother adding to existing stacks.
OPR/DPR/CCWM will be pretty much useless this year due to the way towers manipulate the scores of both teams, see the thread I posted here for a better explanation. Essentially, CCWM rewards teams with high scores, which incentivizes teams to put as many cubes in towers as possible if they want good CCWM. This means that CCWM is entirely unrepresentative of actual match performance.
Skills is also pretty much an entirely different game this year because of the “no colors” rule. Good skills bots will need to score in towers, pick up cubes quickly, and deposit stacks quickly - this is the perfect role for a simple tray with 6-motor drive that stacks in towers by letting cubes fall out the top of the tray.
In a real match, there are tons of different factors to consider, such as defense in the unprotected goal, tower descoring, and needing to pick specific colors to drop in towers. For this reason I don’t think the best tournament bots will also be the best skills bots.