If you had to choose between the Pitti Palace and Medici Palace because of time constraints, which would you chooose? Which is the must-see between the two of them?

thanks!

I wish I could compare them for you, but I've only been to Pitti Palace. To be honest, I wasn't as impressed as I'd anticipated. There was more artwork than historic furntiture. The artwork was grand, of course, but I guess I was just expecting more furnishings of the time period.

If you can only choose one, consider the Pitti Palace. It is a collection of differing museums grouped in and around the beautiful Boboli Gardens. At the top of the gardens is a terrace with beautiful views of the countryside.

Pitti Palace has a few museums in one building. The costume museum on the top floor is really neat , well I think. And, like bas said the boboli gardens which are beautiful.

If you're short on time, the days and hours the two are open may decide for you. Florence seems to have such complicated days and times - e.g. closed the first, third and 5th Sundays; open only from 9 am - 1 pm, etc. We were interested in the costume museum near the Pitti Palace and the opening hours are so short that we just couldn't fit it in.

Some of the museums are not in the main building. For example, there is a beautiful porcelain collection in a building next to the terrace at the top of the gardens.

The Medici-Riccardi Palace is primarily a governmental complex. The most important thing of note is the painted chapel in its interior.
The Pitti Palace was also owned at one point by the Medicis, and also served as the Royal apartments for the House of Savoy, the last reigning monarchs of Italy. In the Pitti Palace, you will find the Royal Apartments, plus a huge collection of artwork, plus a collection of modern artwork, a silver museum, and a porcelain museum, along with the public gardens (Boboli). Pick what you want to see, as there will be lots to do without getting bored.
If, by Medici Palace, you are referring to the Palazzo Vecchio, or old palace, which was owned by the Medicis prior to their move to the Pitti Palace, you will see the Medici Apartments and great painted ceilings. Personally, for a taste of history and the times, I would go to the Palazzo Vecchio. For artwork and modern royal history, the Palazzo Pitti. For a stunning quick visit to a famous chapel, the Palazzo Medici-Riccardi.