10/10 system. I'm literally playing on my SuperGrafx as I write this. Ever since setting foot in Japan I fell in love with this system and I own waaaaaaay too many PC Engine-related gubbins by now, including a PC Engine LT which is one of the most prized items in my collection.
As far as games go, Soldier Blade, Daimakaimura SGX, and Rondo of Blood are some of the best games of all time, and the system has way more interesting games to play, such as Legendary Axe, which is prolly my favourite old-school sidescroller. Its sequel is also up there
And obviously, you cannot mention the plethora of amazing shooters for the system! Hudson, Konami, Naxat (sometimes), Namco just to name a few made so many amazing shooters for this system that I play regularly. I'd love to get Dead Moon as well but that's kind of an expensive one. Other good ones are Hany in the Sky, Cyber Core, Side Arms Hyperdyne, Metal Stoker, Hana Taka Daka, Ai Cho Aniki, just to name a few.
Also if you claim the boxarts are bad, then that's because most American boxarts of this period were absolute rubbish (look at the SMS...)
Japanese boxarts can be gorgeous, look at Soldier Blade or Rondo of Blood for instance