computer buying advice

Hello all

I use Power Pivot & Power Query on Excel heavily. I currently have the Office 365 Excel 2016 Pro plus version (64 bit), running on an i3 a few years old, I love the software but performance is slow and it crashes quite a bit. I have 12GB RAM and 256gb SSD hard drive. My SSD hard drive in my current comp is almost full though.  

I want to buy a new laptop but what aspect(s) should I look at? Ranking them would be great. Or is it that if I buy a computer with certain specs above X the computer should be good enough?

- i3 vs i5 vs i7?

- The letter U at the end vs HQ

- Cache 3MB vs 4MB

- Turbo (all cores) 2.90GHz vs 2.80

- Generation of processor (7th gen vs 6th gen vs 5th gen etc.)

- RAM

- Hard drive size

-SSD vs HHD hard drive

Thanks!!