Welcome to O gauge railroading.
I'm partial to MTH Imperial Railking offerings.
They have more detail than traditional engines but can run on tighter curves than Premier / Scale engines. They also cost less than the high end lines.
As far as Lionel, Williams, Atlas, ect. They are all fine products. I just have mostly MTH.
If you want info on Command Control you can drop me an email.
I run MTH DCS and Lionel TMCC at the same time. Eventually I'll upgrade to Legacy from TMCC but don't need it yet.