All three of the new Apostles come across as good men who will be positive influences and leaders in the Church for the next three decades.
The last time there were three Apostles called in one General Conference was 1906. That time they had George F. Richards (45), Orson F. Whitney (50), and David O. McKay (32). I haven't been able to find why Richards had seniority over Whitney, but there was precedent to seniority not being determined by age when more than one Apostle is called at the same time. Now every time there's been two Apostles called, their seniority has been determined by age. (Kimball-Benson, Nelson-Oaks, Uchtdorf-Bednar).
This time the three Apostles called are Ronald A. Rasband, Gary E. Stevenson, and Dale G. Renlund. Stevenson is the youngest of the three, and my guess as to why Stevenson has seniority over Renlund is that Rasband and Stevenson were going to be the two new Apostles, but then the death of Richard G. Scott meant Pres. Monson wanted to find the third Apostle before General Conference. Or it could be deferrence to their previous Priesthood offices.
Rasband became friends with Jon Huntsman Sr. and worked for him at his company. He eventually became the President/COO of Huntsman Chemical. He retired to serve as mission president of the New York New York North mission. He was called to the Seventy in 2000, and for the past ten years, he's been serving in the Presidency of the Seventy.
He married Ruth Lybbert, daughter of former Seventy Merlin R. Lybbert. She worked full-time as an attorney. When he was called to the First Quorum of the Seventy in 2009, they were assigned to South Africa.
He's someone who can talk heart-transplant shop with Pres. Nelson or chemistry with Pres. Eyring. His talk also reflected that he'll be someone who can pick up the empathy gauntlet left by Elder Scott.
I will say that I was disappointed that all three Apostles were wealthy white men born in Utah, and I know that I am not alone. If you'd taken any of these two men and had the third be someone from South America or Africa or Asia, the world would be buzzing. I think the prophet takes certain people under consideration and prays about them and makes sure they would be good. I can only speculate that maybe if he'd prayed more about non-white and/or foreign-born considerations, maybe one of the three would be different. 60% of the membership of the LDS Church live outside of the United States, and I pray that eventually we'll see more diversity in the Brethren.