Which one should I get Dell Latitude 7450 or Dell Latitude 5550 - for 3 monitors

Hi,

I have 2 external monitors DELL U2415 connected via  WD19TB docking station to my Latitude 7400 2-in-1.

I want to connect an additional monitor to my setup but the DELL U2415 are no longer available.

I need help with 2 things. I need to replace my company laptop now and need to select between  Dell Latitude 7450 or Dell Latitude 5550 - Which one should I pick if I need 3 monitors connected to my setup. What should I ask for as additional specs for the laptop that I select. 

Also which monitor should I get which would not be distracting and sit seamlessly with my existing DELL U2415.

Thanks All

My work is not graphic intensive but I have multiple applicaitons open and need to use RDP a lot. All suggestions welcome. Thanks a lot