Part of the 'fun' of Old School D&D was playing the ability score lottery. Which is why 3.5e pushed point buy so hard; the Rebellion Against the Old School didn't find that lottery to be fun. Now I'm good with point-buy systems in general, but I took an immediate dislike to the 3.5e version. So of course I created my own system for the games I DM.
It's a roll-and-point-buy hybrid.
1. Roll 3d6 six times, and record the scores in order for STR, DEX, etc.
2. Increase any or all of the scores, up to a max of 18, until the sum of the scores equals a campaign-specific value.
3. Apply racial adjustments.
The "campaign-specific" value is usually pretty high (75 to 85), giving average scores ranging from 12 and a fraction to 14 and a fraction, depending on the campaign. I don't mind high starting ability scores, and a player who wants an 18 in a particular ability score can almost always get it.
It also allows dump scores sometimes (if the player gets "lucky" with the dice), but it does not require that a player take one. I dislike "every character will have a dump score," as something required by the rules or even strongly pushed as a practical requirement by the Gawd of Character Optimization.
It also produces what might be called "anti-dump scores," again not always but sometimes. If the player wants a barbarian character and the dice give him an INT of 17, then he can play a barbarian with an INT of 17.