In general, both are exceptional but you're going to have to be a lot more specific to get any kind of decent answer...its like asking, hey have any of you driven a Ford or Chevy?
Tartan/C&C are under new ownership, but did retain Tim Jacket, the principle designer.
Older (say pre 1995) Tartans and C&C are great boats. Typically very well built, and good designs, some better then others. Some are highly sought after boats, for example, my boat sold new for about the same price its worth today, and in some cases, they are worth more today.
Newer models seem to still be well built, designed and $$$, but have been tarnished by a series of cases a few years ago related to warranty issues, design issues, and mostly how the company did not handle it appropriately. No point in getting into the details, you can do a google search on the topic or head over to Anything Sailing Forum
and read about it there. The new owners seem to have the best intentions and a desire to get the brand back on its feet so to speak. I belive Tartan is offering some semi custom options now?