I venture into 1x6’s here recently but just 1x4’s are my go to boards
Yeah that is where I am at. Most of my current expected needs for a jointer are 2-4" with 6" being theoretical. A 4" jointer can do 6 or even 8" boards, just more set up than a wider jointer since you have to run it through twice and ensure both passes are equal. For an occassional board not a big deal. If frequent then hold out for a bigger machine.
In their favor 4" jointers are a little more compact and easier (lighter) to move around the shop than a similar 6"
Delta made a couple of 4" jointers, and I don't know anything about Penncraft other than Delta Rockwell made some of their machines in the 70s.
My particular jointer is branded Homecraft which at one time was Delta's budget line. Often older Delta designs were shifted to the Homecraft line when a new Delta design came along, so they were not really made cheaper, just an older model. Ironically now some of the Homecraft machines are preferred to their contemporary Delta models since they are the same as some early classic Delta models. Mine was made in the 40s, but it is an early Delta design first sold in the late 1920s.
1970s Delta is generally still considered "good Delta" it wasn't until the 80s that they really started to cheapen up manufacture.
As far as price consider that a decent budget Chinese made 6" benchtop 2 blade jointer from a company like Wen or Grizzly will cost $240-270.
Other than width my 4" Delta is better in several ways. It has a 3 blade cutter vs 2, and a longer bed by several inches so can do a bit longer boards. Personally I also like that is is all cast iron, no tin or plastic.