If you can find an older one, get it. I have my Mother’s old Singer that folds down into a cabinet. I also have two newer portable ones. My Mom’s Singer needed to be cleaned and fixed. The man who fixed it said my machine was the last one model made with metal gears. The down side, it weighs a ton. The up side, it will last forever. Almost all machines since the mud 70’s have plastic gears that eventually wear out. I imagine you can get a new machine with metal gears but I’ll bet they are very pricey. I prefer sewing in my Mom’s machine because it feels so solid and doesn’t have much vibration when seeing. My two newer ones just seem too light. In the other hand they all see pretty well. It’s up to you. To you want a big heavy one that is a permanent fixture, piece of furniture in your home or do you want a very functional machine that may not last forever but you can put it in its case and move it easily. A friend and I sometimes see together and we carry out portable machines to each other’s homes. There are videos to show you how to keep your machine oiled, functioning properly and clean.
My most lightweight, portable machine is just from WalMart. I think I paid about $130. I had to buy the case separately. That was maybe $15-20.
Happy sewing machine hunting.