My 2 cents:
1-i7 instead of i5(you need power)
2-AVOID FUSION DRIVES(get SSD if you can)
Unless you get a big SSD(like 1TB), you'll want a separate recording drive(a good SSD can work for a time, but you don't want to fill your system drive with sessions), so consider adding a fast external drive(this can be tricky as most external drives are not fast). One solution is to buy from a company that specializes in recording drives(like Glyph or AvaStor). Another option is to buy an external case and stuff it with either a fast SSD, or a 7200 rpm spinner(WD Caviar Black are a great choice).
I also recommend a big(like 4TB or bigger) external for backups. I would partition that so that session backups are separate from "system" backups
