For Christians who are not philosophically inclined (Aquinas's books require a thorough background in Aristotelian philosophy as well as knowledge of the church fathers and medieval theology in general) there are a few recent options:

• 1994 Catholicism by Richard McBrien
• 2016 Systematic Theology -- A Roman Catholic Approach by a Loyola Marymount Catholic Theology professor Thomas Rausch, SJ
• 2011 Systematic Theology: Roman Catholic Perspectives, 2nd Ed edited by Francis Schüssler Fiorenza

The first one (McBrien's) at around 1,346 pages covers a lot more of the basics than Rausch's 319 pages and have a rather different approach though similar content organization. McBrien's book feels more like a reference book in that a chapter is divided into many relatively independent sections, but each of Rausch's 11 chapters develops the topic assigned to that chapter (like Chapter 6: Sin, Grace, and the Human Person) like an integrated essay covering history, concepts, schools of thoughts organically. Thus Rausch's book seems to be targeted for theology students while McBrien's audience includes laypersons who want to take their Catholic faith one step deeper into the "why", "where" and "what questions. Therefore both books cover the Catholic main ideas as well as the historical framework leading to the present, but Rausch's book offers more of the fringes including somewhat liberal variations. The third one (Fiorenza's) is a collection of essays, so is similar in approach to Rausch's but each chapter has a different author. The book is also twice as long as Rausch's. Both Rausch's and Fiorenza's are strong on theological methods. Fiorenza's generally has better coverage in scriptures.

When compared to Protestant systematic theology textbooks like Louis Berkhof's, John Frame's, Millard Erickson's famous textbooks, I found all 3 options somewhat lacking in depth, although both are better in engaging the world (philosophy, science, humanism) with Fiorenza's and Rausch's one or two levels better than McBrien's. Protestant systematic theology textbooks tend to connect theology MUCH BETTER with scriptural exegesis, especially with recent systematic theologies (although they tend to do poorer with their engagement with church fathers, etc.). Maybe it is because they are a lot more Bible oriented, consistent with their sola scriptura tradition. That is why in addition to one of these choices, you definitely need to invest in all the prerequisites needed to study Aquinas's books, as Aquinas did a masterful synthesis of Bible exegesis, philosophy, Patristics, church tradition and councils, plus his own unique contribution in virtues, psychology, and apologetics. The only areas Aquinas is lacking is recent findings in 2nd temple period, dead sea scrolls, post modern hermeneutics and text criticisms, which Protestant scholars are starting to integrate into their systematic theology textbooks (such as Michael Bird's 2013 Evangelical Theology).

From your need's description I think you will be better served with either Fiorenza's or Rausch's book in conjunction with Aquinas's books supplemented by McBrien's book as reference in areas that are necessarily left out from Rausch's 300-page book. For Rausch's, see Amazon publisher review and a theology journal book review. I think Rausch's is a very good complements to Aquinas since the book puts Aquinas in dialogues with modern theologians and modern philosophers. Here's some excerpts from the Irish Theological Quarterly book review:

I had a student once tell me that she didn’t agree with the Church’s position on a certain moral teaching. I asked her what exactly the Church’s teaching was. She replied that she didn’t know, but that she didn’t agree with it. In the introduction to his book, Rausch mentions Catholicism, the celebrated work by Richard McBrien. This volume might be considered McBrien for a new generation. However, the current generation who present themselves in theology classes do not arrive with the foundational theological knowl-edge and catechetical depth that the students of the McBrien generation had. This is why Rausch’s volume is timely.

Rausch teaches at Loyola Marymount in Los Angeles, so he may have encountered similar comments from students. ...

In the introduction he states that ‘Catholic systematic theology should always be informed by these markers of Catholic identity: a critical realism, an appreciation of sacramentality which lights up the world with traces of the divine, mediation which ennobles both creation and human agency. And communion, underlining Catholicism’s deep sense for the importance of community and the union with God and all people to which we are called’ ( p.xvi). ... To give each chapter fair treatment would warrant more words than are possible here, so I’ll take a couple so as to illustrate the structure and content paradigm of all the chapters in the book.

Rausch deals with Jesus the Christ in Chapter four. He begins with the Historical Jesus and an account of the quests in biblical scholarship to understand Jesus in this context as opposed to the Jesus as proclaimed in and by the Church. He moves on to the Reign of God and Jesus’ mission and then moves on to Jesus’ Death and Resurrection. Then he discusses New Testament, Classical, and Contemporary Christologies. All this is done with a clear and concise writing style, which leaves no room for padding.

...

Kindle eBook version for McBrien's can be purchased at Amazon while Rausch's ebook (PDF, ePub, or Kindle format) can be purchased for download from the publisher, Liturgical Press at roughly the same price (around USD $21). Fiorenza's Kindle eBook version is around $27.

I do not know what protestants use in their seminary, nor am I a catholic priest but catholic priests should certainly learn from Summa Theologiae by St. Thomas Aquinas. It covers everything beginner in theology should know.