RS Tour

I have taken both of those tours, the Adriatic one just this last June/July. Both were interesting but had differences. Have you gone to those two tours' web page and clicked on "Itinerary" to see what is covered each day? Maybe before that, you might want to make a list of your personal preferences as to what you are interested in and then compare your list to what is offered by each tour. You also could go and view the comments of previous tour members on those tours to get a feel for what they thought.
I assume you have those two tours Guide Books, but if you do not that would be small investment when trying to plan and expensive tour to Europe. You did not say when you wanted to go on a tour. In the summer time, both tours will visit locations where it will be real hot. Shoulder season would be best for either if you can go then. Send me a PM if you want more specifics.

I do plan on taking both of these tours as each one interests me. Just can't decide on which one to participate in next year. I have researched both extensively. Will definitely travel in shoulder season.

If you are going to partake of both trips eventually and the only factor is timing, then I would price the flights to each and use that as the differentiator (or pick some other variable and stick to it). If you've already done tons of research, doing more is not going to help much. I don't know if it's helpful, but I have a list of places I want to visit and the order of each will be purely determined by price of getting there at the time I'm ready to go (for example, if there's a fare sale to Portugal and it's cheaper than Italy, then Portugal is moving up the chain to first place - you get the point). I realized I was way overthinking it, and the order doesn't really matter in the end.

In order to decided whatd RS tour I wanted to take, I looked at all the RS scrapbooks on this web site that tour members posted and studied all the photos and read the journaling to see what there was to see and do. This way I knew what looked interesting and what peaked my interest. That is how I decided to go to Ireland. I also read all the comments from the tour members to see how they enjoyed the tours and what they found interesting. If you have YouTube, you can also see tons of videos of the countries and see what there is to see and do. I found this helpful as I am planning my trip to Rome and Istanbul this year with RS tours. Also get the RS guide books from your local library if they have it and read up on the countries, that will also help you decide. Have fun and I am sure whichever one you pick will be great.