My only advice is: buy the best you can afford. Some companies will build to order or without monitor.
My guess is that every post will have a different opinion because they have had different experiences.
Personally, I was glad to have bought a Sony 7 or 8 years ago.
The only thing I have done to improve it is to increase the ram but, I have abused it, been inside it many times changing hard drives or altering the jumpers. And more!
I do it when I am feeling bored. I have learned to back-up first though. Both a second internal and external dives. It has saved my bacon many times.
Earlier computers did not withstand the meddling.