Ideally, it would be nice to see 10 pound differences and split the hw division in two but way too many weight classes is diluting the UFC (maybe not the sport though). The best fix would probably be 6 weight classes at max. This would be my ideal solution for the UFC.
160 - Lightweight
170 - Welterweight
180 - Middleweight
190 - Cruiserweight
200 - Light Heavyweight
240 - Heavyweight
Although this eliminates the big heavyweights such as Lesnar and Sylvia... it will force some of the lhws (the most stacked division) to move up a class and some to move down. Plus guys like Werdum could easily cut down to make the 240 limit.
As for other organizations that targets smaller weight classes like the WEC:
150 - Featherweight
140 - Bantamweight
130 - Flyweight
120 - Strawweight
I personally think WEC should eliminate everything above WW and have 6 weight classes with WW being the heaviest and strawweight being the lightest.
and obviously for Superheavyweight.... 240+