As everyone has said RME is truly one of the best and none of it is going to be inexpensive. But you are build something that can likely last several years as a motherboard / CPU combination. If you can afford the RME, you can't ever second guess yourself about having taken that route.
My MOTU was relatively high end in 2004 and it , as an audio interface , has performed perfectly with Cubase for 9 years. It was only an issue initially in 2005 when MOTU had inexperienced coders developing their firewire drivers. It is a nice feeling clicking this thing on and off for 9 years and having it never screw up. Just like my F-150 with 289,000 miles. It's just does the job
PC Win 7 64bit | VST Instrument Collection | i7 3930 | 32gb Corsair ram : MOTU 896 HD FireWire, Samsung 840 Pro SSD 256gb Win 7 OS | 2nd Crucial 64gb with Cubase 7.5| WD 2 TB Caviar Black | VST via SATA 3 | (2) WD 500gb project drives | 3TB WD network drive | Cubasis and iPad 4th 64gb. Guitarist not really a keyboard player, but tryin' like hell