I really liked the rance 1 gameplay mechanic how do other games compare? I heard rance 3 improved on the 1st one so I was looking to that one.
I only tried Rance 3 (the original) then ended giving up on the game, so I don´t really remember much about the game mechanics. So from the ones I played:
Rance 5d is not that good with the game mechanics, it has a really random system which decides encounters on which you have minimal control. It is basically and easy dungeon crawler with a lot of randomness added to it. So rance 5d will likely feel as a step down from the previous games. It´s only worth to play for important character introduction in my opinion.
Rance VI became more of a tactical rpg meaning managing your teammates, which is still sort of retains the dungeon crawl aesthetic. I feel like at this point the mechanics were already good, albeit a little bit too simple. Rance Magnum is basically the same, only this time they fleshed out the system a lot more, I would say that from their translated games this is the one I enjoyed the most both in mechanics and in content.
Then there is Sengoku Rance which is an absolutely unforgiving turn based strategy, which basically works completely different from any of their games. The game mechanics are really great, but it is frustratingly hard.
About Rance 3, 4 I don´t really know just like you I´m waiting for their remakes to be made\translated.