Help! Receiver or preamp? Im overwhelmed...

What's your budget?   This will probably dictate what we recommend.  Such as under $1000.  $1000-3000.  $4,000 or more. lol.

You can get a used Marantz AV7702 MkII unit for $1000-1300.  I would recommend them because they have excellent power supplies and are the only processor at this price level that have fully discrete analog output stages.  That being said, they do have soft and rolled off high frequencies.  Excellent impact, but if you are using a warm sounding amp it may become too warm/slow.  The Emotiva XPA-5 is a very fast/bright amp and would not have this problem.

The Anthem is going to have much faster attack and better high frequency response, but it could come across a bit bright, especially with your XPA-5 amp.  I don't know that I would go with a AVR receiver because they typically used a single shared power supply for both preamp and amp sections and they aren't that big of a deal.  The processors generally have much better power supplies and are dedicated to preamp only.

If you want something new, the Outlaw 976 is really the only option within your price range.  It's voiced similar to the Marantz 7702, but it doesn't have as good of a power supply and the user interface is rather cumbersome.  It also doesn't have the discrete analog output stages.  The Marantz is a better product here, but you have to buy it used.  The AV7702 is not going to be more than 3 years old (not really old at all).  The 7702 is also pretty current for HDMI (4K and HDMI 2.0 support).  There's actually a mkII on audiogon now for $1,000 even.

Denon doesn't have a processor, so you'd have to get an AVR receiver.