You are going to get all sorts of answers to this question. Really it is going to be a preference, and also how you use your jeep the most.
I am a fan of the monotube shocks myself for offroading. (OME, Billstiens) but they tend to be more expensive, and not really necessary for a daily driver that doesn't go off-road. For a cheaper good shock the Rancho 5000X are popular, but they are a dual tube shock. I am actually running those myself right now, but plan on upgrading soon enough, but I have not complaints for them as a daily driver.
I would say the Rancho 5000X will be the most popular solution, because they offer a good ride at a decent price.
I can't tell you the best smooth ride because yours and mines definition might be different. I ran the OME (Old Man Emu) Nitro sports with my 2 inch lift, and absolutely loved them, but when I went to my 4 inch lift I ran with the Ranchos because of the cost. Although, I don't have a loving relationship with them as I did with my OME, they are pretty nice.
That is my two cents worth