Most of the time with most auto makes the answer to your question is whatever makes you feel warm and fuzzy. However, there are real considerations to think about with these hemi's and the problems that come up in the cams and lifters. The first thing you should consider is weight, do you think the twenty weight is adequate protection? Almost 1/2 of the forum says no in a recent poll here. I'd use 5w30, and I do use 5w30, and think it is a real good idea.
Filtration another real important thing to consider, see my oil filter thread in my sig. Spun Microglass a real good thing to consider, choose a brand you like doesn't really matter, but the media really does matter.
Oil brand, if you choose 5w30 then you already choose to have more protection on the metal, so hearty oils might be less important. FCA realizes the benefit of having a high detergent oil in the hemi, that is why they helped build Pennzoil Ultra Platinum 0w40 specifically for the 6.4 hemi. So a popular strategy here is to mix PUP 0w40 with some PUP 5w20 to get a higher moly level and good film strength in the 5.7.
Don't let the 40 weight scare you, it is not a thick 40 weight and if you chose to mix it 3 qrts to 4 qrts 5w20 it is a very good strategy. Or just get 5w30 PUP, this oil has proven itself to be the choice of the forum, as proven by the poll as the most used oil here.
If you have hemi tick, there really has been only one proven oil IMO, Redline 5w30.
The information you get here is biased, but biased in a good way. The forum has had the privilege of seeing over 5 years of results, so the body of knowledge is biased towards what worked for the most people here. These hemi's are finicky, I would stay up on my maintenance.