I have the SS1, but have installed snugrides, an evenflo and an older babytrend. By far I prefer the SS1, but thats mainly because I have never had to take more than 3 minutes getting it in perfectly (using the base and a seatbelt) and always have an absolutely no movement install (in 3 subarus, honda van, older 80s 2 and 4 door cars, grand am, a extended cab truck, tons of different vehicles).
Again, I havent had the chance to try latch or the newest versions of the babytrend/evenflo but thats my .02 on it. With the others, it didnt take more than 10 minutes but the ss1 just seemed more fool-proof to me.
As for the strollers Ive only used graco and safety first. I liked how the safety 1st folded up, and how it reclined (with a strap fully adjustable rather than different levels even though it didnt go all the way down). I liked the brakes on the graco (it was a full shelf across instead of just on the wheels) and its canopy better (smooth and didnt fall off) plus the fact it did recline all the way.
Other than those things I had no complaints about either, good storage and both fit my graco carseat. At 19 months I still will take my son and put him in the stroller in his car seat so I do think its worth it to get one that will take the seat you get.
As for some things you could make a list of specific things they might overlook in the manual (if the handle can be up/down, where/if they can use latch in their car, how tight the harness should be, a note about winter attire etc) and send it to them with some baby stuff to let them know they are commonly overlooked.
Sry this was so long, but I thought Id give you detail because who knows what you prefer especially with the strollers.