Zander

Well I would say Reborn is tougher because the variety. With insurgence I feel that once you got your team down with minor changes you can get through most challenges pretty comfortably because they are pretty similar. The game focuses mostly around hyper offence.

This issue I have less with reborn because they try to change the type of challenges all around. So you can never be too comfortable or get your ass kicked. That being said Reborn is also reaching the limits of its challenges.

Hmm so you prefer diversity in your challenges rather than simply using and winning with hyper offensive pokemon. I wonder how old I'll need to be to get that kind of attitude. I just love offense and no other style suits me. Even stuff that stops offense like a pure wall is not okay with me, much less using stall pokemon. This also tends to be the reason for me not liking field effects because it stops me from attacking properly. 

Mega Salamence wails on nearly everything in Insurgence, tho. You get it pretty late, but before the end of the main storyline iirc.
Insurgence has a lot of non-canonical Mega's (and OP delta mons) it uses against you that get 'optimal' set-up in those challenges, when those same mons can be difficult for a player to use without being overly time-consuming or are available way later in-game, e.g. Delta Volcarona.
Also, if I'm correct, it has a system that auto-levels your opponent to the highest level in your team for some battles, while for others it relies on ramping up the opponent's levels quite drastically to keep you from overleveling too much. Unfortunately, with the races you can grind enough money to to so anyway through your secret base.
Reborn only uses a handful of PULSEs which cannot be caught, while having level caps and limited availability. Suddenly you start to appreciate Kricketune and Trubbish.
On top of that, since field effects, the metagame in Reborn is drastically different from normal games. A run-of-the-mill OU-team could get hammered in Reborn against seemingly lesser mons (e.g. gym battles?) because of those effects. So, it might be comparing apples to oranges overall.