I recently broke my rear Derailleur in my Super Sport 700c SCHWINN S35408M10DSG-LG 7-speed hybrid bike. I tried the Shimano Altus MTB rear Derailleur but I don't like it as much, it feels a bit harder or stiffer to pedal. I appreciate any recommendation or suggestions for a good or great rear Derailleur for a hybrid bike.
Based on the information supplied, it appears that your original rear derailleur is a Shimano Tourney RD-TY300. This is a relatively inexpensive rear derailleur, and for your purposes, I would simply replace it, like for like. The Altus RD you tried to use "may" have a different pull ratio or than what your shifters. I did not think that the Shimano pull ratio was different on these up to 9 speed (the Altus appears to be a 9-speed derailleur), but I could be wrong.
To find a direct replacement online, search on "Shimano Tourney RD-TY300"
I found a link to Amazon and a couple other places just with that search.
Searching on your bike revealed the RD is what is shown in this image
Ensure that the upper mounting point is the same. There are two versions of this RD out there. Make sure it looks like this:
and NOT like this (unless your original one did look this way):