In general, I prefer a cap. That said, there is some merit to games that have a cap but not one that one could reasonably reach. Eve Online for example has a "cap" so to speak - at about 450 million SP. After nearly three years of playing my character possessed about 40 million SP. As a rough estimate, the most SP one can train in an hour is under 3000 (I personally maxed out at 2240sp/hr but I'm willing to accept that with very particular builds it can be nuded higher, and that there are slighly better learning implants than the ones I used). The cap has also shifted ever higher so, it is effectively "uncapped" simply because nobody has ever reached it (or even come close for that matter). There are plenty of caps in the game however - one can never train a skill beyond level 5 and after a paultry 60 million SP one can be fully skilled in every applicable skill for every type of ship a particular race flies.