Im going to go ahead and echo the sentiments of many other explorers and ask for more variable stuff out there, alien ruins, ship wrecks, ANYTHING to spice up ice and rock balls, it doesn't even have to be worth money, just something to read or look at or feel proud that I saw. Even "anomalies" in space that randomly appear and disappear would be great.
The other thing though that Im noticing is that most of our ships have at least a few empty slots, either weapons hardpoints, utility points or or empty slots filled with cargo racks we never use. I would love to see more tools to bring back more, and different kinds of data. Atmosphere scoops for ELPs or anything with an atmosphere. Some kind of mineral sampler, or organic sampler to bring back pretty rocks or simple life forms. Maybe devices to measure background radiation, or anything else really. Or how about an "experimental scanner" that can be used inside black holes or those previously mentioned anomalies for bigger payouts due to potentially high risk situations in scientifically important areas.
Importantly these things should not all be able to be carried at one time by any given ship necessitating multiple trips, or focusing on certain data collection on a specific trip. i.e.: "I dont have room for that experimental scanner or radiation scanner because Im bringing an atmosphere scoop, a water sampler, a mineral sampler and a cargo rack to maximize my profits from ELPs instead of focusing on anomalies and experimental data"
Basically give us more scanners, more tools, more lenses, more scoops, and a reason to have a cargo rack to bring back samples and goodies from space. Let us really fit out an exploration and science vessel. It would make each explorer a little more unique in not only where they're going, but also what specific data they're looking for, and what they're bringing back. It may even make some ships more viable as exploration ships (Type 9 etc) simply because they may not have the jump range but they can carry more scanners and equipment, and have more room to bring back samples. A type 9 with the standard exploration equipment, an organic life sampler and stacks of cargo racks for example could be something of an "arc" ship, setting out to bring back as many lifeforms as possible.
Let us get out there and do some science while were exploring.
EDIT: Just realized that could also add another level of "first explored" by granularity, by having a first discovered by, first sampled by, first measured by... etc. tags. That way even if someone else has FOUND an earth like planet, someone else may be the first to bring back life forms, or examples of its atmosphere/water/soil/technology/whatever
EDIT2: Also just realized that hellhawk pretty much beat me to this one. And about 7000 systems Ive passed through

. Its worth repeating though if the devs are reading.