Access:
-dutapark : closer to klcc (if going there for work) but need to make a long turn (if going back home from klcc). Traffic by pass schools, which is good.
-era: going out to klcc easier as can use the link bridge (only exclusive for residents ) , going back home from klcc , you can either go through the front entrance (segambut) or take the mitec entrance (from jalan kicking road) and make a uturn to link bridge of the era. I would prefer the latter as traffic can be heavy taking the segambut way. Traffic bypasses schools. Which is good.
-riana: too deep into segambut that I don't bother considering there. Traffic too hectic.. Traffic passes through several schools. Which is not good.

Location:
Dutapark: near river, and slightly submerged the ground level vs the main jalan kuching road. In the middle of nowhere.
Era: if the mrt 3 location next to mitec does materialise, then era will only be 700metres walking distance away, which is only 7minutes walk. Which makes it very walkable distance to the KL metropolis. Nearby schools as well and other amenities.
Riana: nothing worthy of mentioning..

Developer: Can't really comment as I've no experience with these names yet. But what I can say, if jkg wants to make their foray into klang valley a success, they must not fail their flagship Era project first. It's all about reputation...

Investment or rental. Tough to make a comparison. But I think yield wise, if the mrt 3 and kl metropolis does happen, era would bring better yields. Likewise on capital appreciation. This is given their closer and proximity access to Jalan Kuching key amenities.