Alternative Proficiency System (5e)
This system of proficiency allows more variance in the level of proficiency in various aspects of the game to span the gap between 3.5 and 5e so that players that enjoyed the variation in skills in 3.5 or just dislike that¸ short of rogue or bard expertise¸ you only have proficient or not proficient in all skill¸ tools¸ weapons¸ and languages. The concept of gaining a skill and immediately being as talented at the new skill as the skill that you use every day seemed odd¸ same with languages. You are either proficient with a language like it was your mother tongue or you are not. You might have spent your whole life training to master fighting with a longsword but as soon as you pick up a war hammer you are just as effective with that. This system allows for character growth and time commitment showing a quantifiable difference to the character's learning and ability.