2HP Arp

From twohp.com, 2HP Arp, which seems to be low or out of stock in most places at the time of writing, is a lot of bang for your buck, retailing for about $109.

This is the simplest way to go from something completely abstract to something more "traditionally" musical, if that's what you're looking for.

I don't like the hole placement on the front panel of mine.  I'm assuming I just got a bad cut, but it seems to be off by about a millimeter, causing it to not set properly next to other modules, unless I flip it upside down.  The text is also printed vertically-off so that the labels feel like they're closer to the wrong patch point.  (So, unlike the one pictured which looks good, ROOT on mine is written so that it is almost touching the patch point below it, which is actually the point for selecting the arpeggio type.)  That being said, the layout is simple enough to learn without relying on the panel text, so it isn't that big of a deal.

At only 2HP there's not really a way to beat this.  Even if you have another sequencer, slowing that one down and patching its Gate out into the Reset input here, and patching its CV out into the Root input here, and running a multiplied clock into the Trig here, will turn a simple sequence into something so much more sparkly and extravagant.