Stellaris is ironically Paradox's most accessible game and largely because it's a mile wide and inch deep. Lots of systems, lots of potential (especially in empire creation), but once you dig down you quickly realize there's little there. Combat is an utter joke, there's not much separating how machines, hive minds, and normal species play, and for all the toys you get (megastructures, juggernauts, colossi) in the end it all devolves to galactic map painting. Not helping either is how the game chugs horribly in the mid to late phases, enough so they stuck a bandaid over it via pop growth curves since correcting it would probably necessitate a brand new game - and the later phases are of course where all the interesting goodies lie. To Paradox's credit they seem to acknowledge this given the indication of adding unique mechanics and fleshing out traditions, but personally I'll believe it when I see it; the company as a whole is too wedded to its DLC model and is coasting hard on its reputation.
I will second Endless Legend and Endless Space 2 though, especially Legend, they feature some of the best empire design in the genre given the radically different approach to each faction and provide some RPG-lite quests and structured quest victory conditions to provide tangible objectives outside the usual expectations. Also Amplitude kills it when it comes to art, soundtrack, and most importantly GUI: their games look and sound incredible, even if some aspects like the combat systems can be tedious at times. Really have high hopes for Humankind, especially if it can finally light a fire under Firaxis' ass.
Also another one to pay attention to this year for any space 4x lover is Distant Worlds 2. The franchise is far less known than Stellaris (it's published by Slitherine Software), but it destroys Stellaris when it comes to economics and the sequel looks like it'll improve on it in all aspects.
