V3max is a solid handset. I am using it for the last few months and it is a recommended handset from my side. However after recently acquiring a vivo x5max I must say I like it more than my v3max. However I do not play games.
I guess there was no significant update took part in marshmallow. So I find it better to stay in lollipop than update to marshmallow and encounter a lot of bugs which may render the handset unusable. Playstore apps doesn’t require you to have marshmallow right now. I’ts just for people who wants to brag to others that they have newer version of android. If you want a new version, why not get a phone with nougat version.