I prefer the 3d6.
It's bell curve would prevent rampant stat increases, would serve better to recover damaged stats and limit stat increases beyond 18.
Oh that's cool for me too
I just wrote probabilities for 1d20 because they're easier
The proposed d20 system would do poorly in those areas, IMO. And it can be gamed. As written, I would always roll my highest stats (not lowest), knowing that I have a likelihood of increasing my stats with a d20 and also knowing that I could easily address my lower scores if I failed at boosting the highest ones.
I'm not sure about this. I might really want to get rid of a penalty rather than getting a +2 STR; besides, having to roll your 15 STR and failing the (thin) 25% chance (or less, if you're using 3d6) to improve it, means you'll probably end up gaining a +1 in another STAT, which might as well be your 10 PER.
And the higher the stat increase, the easier it is to acquire the next bonus (e.g. 9-12 = 0, 13-15: +1, 16-17: +2, 18: +3). So I'm rewarded for having that higher stat and rolling on it too.
that's a problem with the bell-shaped bonuses
i agree that with 3d6 it's better, but still you're going to see that, starting at STR 13, the first 2 increase make no difference, the next 2 bring a +1, and the last one another +1... it's still weird, isn't it?
A character with a 17 in an stat only has a 3% chance of increasing to 18 using the 3d6 system. With the d20, there is a 15% chance of increase. And what happens when a character with an 18 rolls a 19 or 20? There's a 10% chance of that happening. While it's a non-issue with the 3d6 system.
Well with d20 it was obvious that you'd get to improve a 17 on a 18-19-20. And that you can't improve a stat over 18!
With the 3d6 system, I'd be mentally injured if I neglected to roll on my lowest stats. They have the highest chance of success. And there's no "do-overs" as with the proposed d20 system. No going down the list of abilities until I get a success. So if I get clever and decide I want to try and roll over my INT of 15 and roll a 13, I'm done. There's no safety blanket waiting for me to address my 6 Stamina. By all rights, I should've rolled 3d6 against my Stamina and will be kicking myself throughout the next level or two to do so.
That's the point: i'd like the warrior to get a nice chance of buffing up STR even if it's 15 already, i don't want him to raise INT that's just 5. Who cares for that anyway!?
By going through the list of skills, he might end up with increasing INT anyway but at least he can juggle the probabilities a bit with the order. And the thing that really boggles me is: think you are the 10 STR Warrior. You got three chances to increase already and always got under your not-so-cool STR. Another player, a wizard, with already 14 INT, rolled 3 times and got +1 two times, so he's at 16 now. Despite the brilliant equity of the 3d6 probabilities, if you're rolling only a few times anything can happen. Since this increase is something that you get only every other level, i'd like that everyone got something at least. Your warrior in the example above might not have increased his STR but maybe got +1 STA +1 AGI and +1 LUCK over the 3 increases. Not too bad, and generates ever growing, unique characters...