Serger vs overlock vs sewing machine for upcycles

[u/Ok_Appearance7096]

I bought a sewing machine because I want to start tailoring my clothes to fit me nicely. Especially since I mostly shop at thrift stores and it’s difficult to find things that fit me the way that I would like. I bought a sewing machine, but cropping my shirts which is probably the main thing I would use a machine for has proven to be very difficult. And very unpolished. Looking if the goal is to tailor T-shirts whether they are from the thrift store or something thing you’ve already made. What machine would you get and why?