I wouldn´t think too much about other engines for now.
RPG MV is a solid decision, only MZ is more actual, is very similar and has few "new" options to offer, like the layer option, which existed in RPG XP, but was dropped in VX and MV. You can use the MV tilesets in MZ, but not the plug-ins, therefore it is a money decision.
Tried the WOLF engine myself years ago, but switched back, because there was not much community support that days, don´t know how much changed.
Renpy, I really hate to work with that engine. The engine is not as simple as most of the Renpy games look. And as far as I know you, you don´t want to create a basic Renpy game (text and picture clicker) and it is really picture heavy. In my opinion, there are only a few Renpy games that show what is really possible with that engine, like
Fashion Business,
Bright Past or
Special Request.
Unity, didn´t try it myself, but I am impressed by the variaty of possiblities. You can create strategic games, RPGs or even Renpy like games. But I really don´t know how complex the engine is and how much mods/DLCs you need to work on something specific. The best adult game example I can think of is
Hail Dicktator.
The games above are only examples, if you want to have a look some games and not the engine only. If you want me to delete them, because I should not advertise any games here, just write me.