Skill Points gained for a level is 5 + Level/10 (Drop fractions) so 5 at 2-9, 6 at 11-19, 7 at 21-29, etc.

XP required for increase to a level is 1000 * (Level - 1) so +1000 xp to go from level 1 to level 2, +2000 xp to go from level 2 to level 3, etc.

The genie lamp equates 10,000 xp to 8 skill points, or 1250 xp per skill point. A quick look at the ratios you get for the formulae above show that the xp per skill point is higher than that for all levels 8+ (1400 at level 8, ~5000 around level 50). Since it's your current level that affects which was a better deal, and not the level you were at when you used the lamp, the skill points is a better deal if you plan to ever train above level 7. And given the amount of XP available in the game, if you don't plan to train above level 7 you'll have no use for the XP anyway.