How are you paying for lift access at Keystone and Breck? Crested Butte is now owned by Vail, and comes with discounts and access on most passes. You might be able to visit CB, without extra ticket costs.
If you can visit Crested Butte without any extra cost it should be a no brainer choice. There is less for intermediates here than places in Summit County, but enough for a couple of days.
Wolf Creek is also going to be a cheaper option, over a place like Telluride.
To cut down on cost and driving (Telluride is nowhere close to Denver) you should think about some other hidden Gems. "Ski" Cooper in Leadville would cut travel by keeping you near Summit County, but make the crowds vanish. Monarch will be another area you will drive right by if you head south.
If you are trying to explore some area, need to be back in Denver, and don't mind the smaller size: "Ski" Cooper in Leadville, Monarch, CB if it makes $$ sense on some kind of Epic Pass, and then Wolf Creek if it is cheaper than CB though longer drive.
If you have Epic Pass access Telluride obviously makes sense, but travel, lodging, and food will make it a lot more expensive.
If you do Monarch, Cooper, or both, look into the Colorado Ski Country Gems card, as a discount option.
And as always, if you can wait to book and buy things, and cost is not a factor, just go wherever conditions are best. Locals on here are always happy to brag.