As mentioned earlier, "which is better" is really too broad of a question. Looking at just about any two planes in the game you could find one or the other that is "better" depending on what attribute/characteristic is in question.
I'm going to go out on a limb and guess that you are new the game (my apologies if that is incorrect). Between the two planes I would say that the 190's (especially the D9) would offer a shorter path to initial success, while at the same time offering less options for ACM to the newer player. The 190's are more stable than the 109's and have a gun package that IMHO is easier to hit with and are fast enough to help keep you out of the tower. Outside of the 400mph boom and zoom/run gameplan however they will be harder to have success with for the newer player. Easier, but more limited.
I think the 109's are a little different, the earlier models, 109F, 109G2, are easier to handle, than the 109K, and are more nimble as well but slower. The K has enormous power up front that can be a little tricky to handle at first and the 30mm will test your aiming for awhile. If you get over initial troubles I think the 109's are more capable fighters in general than the 190's.
These are just my impressions, I should also mention that I actually have very little time in either type.