I just got back from doing back to back tours, the first with Contiki and the second with Topdeck (both hotel tours, so I don’t have experience with camping tours). Whichever you choose, you will definitely have a great time, but if I was going to pick one over the other then I’d pick Contiki.
I had probably the complete opposite experience to Stacey. I felt on Topdeck that I was forced to go on the orientation walks with the group. There were a couple of times where I would have preferred to do my own thing, but felt pressured to go with the group. The orientation walks felt quite rushed and if we stopped to take a photo we would practically be scolded and told to hurry up. I just felt like there was very little flexibility, as opposed to Contiki where we could leave the orientation walk and do our own thing, as long as we got back to the bus or to dinner on time.
I felt that Contiki was a lot more organised than Topdeck, in a good way. It was nice knowing exactly what was going on and when. Topdeck was a bit more go with the flow and you only really found out what was going on when you got to a place. I liked being able to plan my day knowing that dinner would be at a certain time, or that we would be in a town for a certain amount of time.
I felt Topdeck was more rushed in general. Lunch stops, toilet stops, stops in cities and at certain sights all felt like we were pushed for time.
I never felt like I was forced into any optional activities on either tour. I pulled out of an optional on both tours due to illness and had no issue with a tour manager getting grumpy over it. I liked how Contiki took payment for all optionals straight away, as opposed to Topdeck who would collect the money as the tour went on. I found I never had the right amount of cash on me (as we were never given much of a warning). On both tours the optionals were great.
I did hotel tours with both companies and found Contiki’s accommodation to be of a higher standard than Topdeck. Some of the hotels on Topdeck were awful.
As for provided meals, there was a better variety of food on Topdeck. Contiki was the same thing over and over again (lots of chicken and soup!). Both tours the food was better than I expected.
Both groups had a huge range of ages, 18 up to 37ish on both tours I think. There were always people willing to go out and party on both tours, and I never felt forced into going out drinking. I did find that people on Contiki were more into getting to know everyone else straight away, and I felt like I got to know everyone on my two week long Contiki tour a lot better than everyone on my three week long Topdeck. There were a lot more couples and groups of friends on my Topdeck tour, more solo travellers on Contiki.