I have never owned an 1815 but have owned a 1st gen Datograph twice. I prefer the Malte for comfort AND looks. Everyone always focuses on the architecture and beauty of the Lange movement but for owners of the watch you will see the dial side 95% more often than the movement side, this coming from a movement snob ๐๐
I also own a Patek 5070G, a couple Duometres, and several other high end chronos. Besides the Duometres which are my absolute favorite high end chronographs (simple chrono, not rattrapante), the Malte would be next, even above the 5070G. I just love the Malte dial and prefer the case and lugs more than the 5070.
As for value and future value, that makes no difference to me at all. If I wanted something to gain in value, I would not waste my time with watches, LOL. Bitcoin, ethereum, etc...would make watch values and future potential just look silly.
If you have never owned a 5070 Tony, I would highly recommend one. Not because it is more collectible, but because it is just a beautiful watch ๐๐

