Jameson's or Guinness ?

what do you prefer Whiskey or stout, make your choice on that,you will get to taste the stuff.

The distilling of whisky and the brewing of beer/ale/stout are two different things. I don't think either of these are like a tour where you actually see the process. They are not currently active distilleries or breweries but rather tours of the actual premises where it was done in the past. Both have some actual historical equipment on display and films that show the process and some memorabilia. And of course they both have the tasting rooms at the end of the tour so it depends on which you want to taste - and of course the GIFT shop, nudge nudge. The Guinness gift shop is huge, Jamesons not so much.

I've only done the Jameson tour in Midleton (which is still in operation, so a completely different experience than is offered in Dublin) but the Guinness tour was mildly interesting. The pluses are: it is right on the hop on/hop off bus route, so you can see a good chunk of the city as well as stop at the brewery; the 360 degree view from the tasting room at the top of the building is wonderful, at least on a relatively clear day; and, if you are in need of sustenance, the cafe serves a lovely Guinness stew with brown bread.

I've done both- twice. I recommend the Jameson distillery tour over the Guinness tour. The Guinness storehouse is a self guided tour with signs that describe the process. The Jameson tour is led by a guide and I found it to be a better experience since there is someone actually describing the process and you can ask questions if you like. They select 4-5 individuals at the beginning of the tour to participate in a whiskey tasting panel which is a really fun experience (everyone gets some Jameson at the end of the tour though). The one thing I felt the Guinness tour had over the Jameson one was the views from the Gravity bar at the end.

Have not been to the Jameson but did Guinness one and did not enjoy it, but that is our opinion. You certainly might feel differently but be aware if the day is rainy, overcast you might not see anything from the roof top bar.

Rosemary's note seems to be steering us towards Jameson's. I have never been a personal fan of Guinness, preferring Harp instead. The fact that there is not a guided tour is also a deciding factor. If no guide, then is the Guinness exhibit a stroll through a grand commercial with a pint at the end?

On the Guinness tour it is pretty much a stroll through. There are some videos about the brewing process and they direct you in a certain direction so that you see pictures/videos of the process from start to finish and then you get a pint at the end in the gravity bar, which as mentioned by someone else does have 360 degree views of the city . I vaguely remember some exhibits with old ads and stuff too. The space is huge and to me it just seems bland and not super informative. Also, I love a pint of Guinness so that does not play into my indifference to the tour at all. I actually enjoyed the shop at the end more than the tour, I still have an apron from my first trip that makes me happy every time I use it.