The one which started it all in world of freeware for patches, at least of which I know of :
Spatch .Obj support by plugin, I think, u can convert the files it exports anyway.
An interesting and later variation. I just don’t like how it locks in rotation when rotating 360º…but VERY useful and good tool
Hamapatch. Strongly recommended.Obj support .
Another later flavour, and in very active development last time I checked… is java, so all can use it with a JRE… I do really love this tool, I hope to see it evolve. My main tool is wings, but is sweet to model with patches soemtimes.
Jpatch . Is having bones and planned animation support.Obj support .
Ayam seems a very advanced nurbs modeler in the free world. Obj support .
Go get it too if interested in these o additional ways in modelling.
Obj support, or similar, can share meshes with Blender very easily.
I got in love with polies and subdivs long ago, but I still like to model like I did before: metaballs, mesh-smudging, or patches.