I've stayed at the Ritz. Very nice. Isolated. I'd probably go for the Sharq Village and Spa before the Ritz due to the distance from the airport.
I haven't stayed at any other Marriott location but I'm familiar with the city; I've also stayed at the Four Seasons.
The advantage of the Marriott and Sharq Village is that they are close to the airport. It's been ~3 years since I've been to Doha but the traffic can be terrible at all times of day and night.
What time of day does your flight leave Doha?
Based on your itinerary, I'd go for either Sharq Village (a Ritz property) or the Marriott.
Next on the list, I'd go with the Renaissance, followed by the Courtyard. (They're colocated so I suspect that there isn't much difference between them)
My last choice would be the Ritz due to the distance from the airport; you're not staying long enough to justify that much driving time.