A lot of the complaints about SH5, stem from the fact a fair bit was omitted that had been present in previous versions, and some folks started behaving like chicken little because x, y, z was no longer available without modding. The game does have problems, just as all the games in the series have had at launch, but is still enjoyable in its own right.
Should you choose to start with either 3 or 4 I should warn you about trying the larger mods as a beginner, they tend to focus on adding greater realism and offering a more accurate historical perspective, and for that reason offer considerably greater challenge than either title run in vanilla, potentially, far too much for someone new to the genre. A slap for everyone who didn't consider this before suggesting a super mod to a new comer.
I would suggest trying whatever title you buy without applying any of the larger balance altering mods at first, then, once you are comfortable with the core concepts and ready for more challenge, start ramping things up with the super mods.