yes, they do retain dirt. That's why I have a set of chrome handled ones for use in situations where there's a lot of grease and ****. I started out trying to buy or make ratchets with the screwdriver-type hard handles but the more and more i used them, they more often than not seemed to get in the way on the 1/4 and shorter 3/8 ratchets. So, now, I do still have a few hard handled smaller 3/8 and a couple 1/4 but for the most part, all mine are the newer style comfort handles. the best ones IMO are the colored ones with the black trim that they put on some of the 36 tooth ratchets. theyre a harder plastic making them easier to clean and theyre still not as bulky as the screwdriver handles. I do, however have a big screwdriver type handle put on one of my 24 inch breaker bars. I just fiind that having a bigger handle on it allows me to put a little more grunt into it.
as for my preference, i prefer the feel of a comfort handled ratchet but I prefer the easy to clean properties of the chrome ones.