When comparing 13th Age vs Lamentations of the Flame Princess, the Slant community recommends 13th Age for most people. In the question“What are the best tabletop RPGs?” 13th Age is ranked 27th while Lamentations of the Flame Princess is ranked 28th. The most important reason people chose 13th Age is:
The world is half built, letting you get in and leave your mark. Each class plays mechanically different than other d20 versions. Skills are placed by backgrounds. It's a short hand and interesting way of playing DnD.
Ranked in these QuestionsQuestion Ranking
Pros
Pro The game is built for people who've done it before
The world is half built, letting you get in and leave your mark. Each class plays mechanically different than other d20 versions. Skills are placed by backgrounds. It's a short hand and interesting way of playing DnD.
Pro Long lists of skills are gone completely
And covered by backgrounds (much like FATE or Cortex+) so that players aren't searching through lists of skills and what they can do constantly.
Pro Gonzo without the grid
13th Age has some very gonzo fights with party combos, lots of variable powers for monsters and PC's but as a simple set of rules for combat that speed it up without losing a lot of options.
Pro Characters don't ever become too powerful
Pro A different take on magic
Pro Streamlined
Simple, streamlined rules for old-school crawls (most of them organized alphabetically).
Cons
Con Too similar to 4th
Con The Icons and the PC relationships to them can confuse
Can be confusing, especially for new players.
Con It doesn't really do anything new, it just looks pretty
Con No power gain
Characters don’t ever become too powerful.