dell or lenovo thinkpad.... really confused... any personal suggestions. will be mostly used for visual studio and SQL server.

Get something with a solid state.

mac

even if I use Linux on client (probably you need windows), I'm happy with my dell xps 13". The only issue is the docking station to have more than one monitor: the USB one is slow, the thunderbolt one is too new, don't works on Linux and has serious problem also on windows.

if you are going to be doing typing on the laptop keyboard, HP ProBook or Lenovo T series. I am a big fan of business laptops with good keyboards and matt screens though. SSD is my other new requirement. it is difficult to go back to a spinning disk after SSD.

i am thinking of lenovo x series.... used it a while in work....

ran win /linux on mac. mac got a state of art hardware and I have never seen win/linux running so fast on any other hardware.
P.s. next time mention a reason for downvote

go with thinkpad...ive got Thinkpad T450s