I LOVED the tours my family took through the neighborhoods of Buenos Aires. The owner of the company, Alan, was incredibly responsive to our late requests for tours... not only did he promptly respond to my email inquiries, but also utilized WhatsApp to help me figure out the tour for the next day. He definitely went above and beyond in customer service, and we were so grateful.
We did two half-day walking tours (it's great they let you split them up like that... it gives you more time to explore!) We did the San Telmo/La Boca tour and the Historic City Center tour, since we were staying near the Recoleta Cemetery and had explored it on our own. (Side note: I highly recommend the La Boca tour as it's far enough out that you might not get there otherwise, and it has a very unique history with a fun vibe). Our tour guide, Richard, was incredibly knowledgeable and really helped tailor the tour to our interests. At the end of the first day he led us to this amazing little wine bar where we did a tasting (at our own cost), and we loved the wine so much we brought home 6 bottles!
Later in our trip we also booked a full day tour to Colonia de Sacramento in Uruguay. Oliver leads these trips, and he was very helpful ushering us through the customs process and getting our ferry tickets for us (something that proved to be impossible to do online, without an Argentine credit card). He had a lot of insight into the history of this UNESCO World Heritage site.... that said, I found the city to be rather dull and uninspiring. The buildings from the 1600's were not very impressive and the old town is pretty small. I may be jaded because I travel often, but it really didn't wow me. On top of the underwhelming town, we had a horribly rainy and cold day. One thing I wished Oliver would have done is adjusted his tour to the weather.... yes he can't control it, but when freezing rain is pouring down, maybe decrease the 'free time' portion of the trip to get back to the ferry earlier to wait in a dry area. We missed the whole mate experience (something the entire family had been looking forward to), because we got to the ferry late and then had to all sit separately. Meanwhile, we spent 2 soggy hours trying to avoid the rain in unheated and very small museums. Since we paid a high price to have a private custom tour, I expected a bit more adjustment to the circumstances, as unexpected as they were. Not to mention we didn't get one of the experiences advertised as included in the (steep!) price.
Summary: DEFINITELY do the tours in Buenos Aires, and ask for Richard if you can! :) Only pay the very high price to go to Colonia in Uruguay if you really, really want to see Uruguay and you can't speak Spanish to get ferry tickets on your own.