It depends on your ship, build, scooping and exploration styles. If you have a big scoop and always scan the primary, I'd prefer to have the single jump range and less fuel, topping up on every scoopable before the scan even finishes. It also depends on the type of exploration you do as well. But, different people, different preferences. I saw an anaconda exploration build once that was basically a flying fuel tanker with maybe 25ly range. Owner claimed this is great as he does nearly 1000ly without scooping than goes make tea as he tops up with a measly class 3 (or something low like that) scoop. Hardly what I'd call optimal, as you gimp the main advantage of the conda by giving her such a range, but he likes it. I still wouldn't advise that route to people, though
Naturally it depends on style. As someone who only scans the primary star if the system has other bodies worth scanning, this works. Flying a tanker however is not what I'm advising at all - that's likely a lot worse in terms of travel speed. With 25 ly jump range, I have no clue why you'd bother with an Anaconda. That said, in the nearly 200k ly I've flown, I've definitely seen a pattern where even with big scopes, you don't refuel fully AND fly far enough away from the primary star, in the time it takes for the FSD cooldown to go away. This is especially true for the hotter / larger stars where it takes longer to get out of the "too hot to jump" area. Also well known for smuggling missions - it's better to use fuel tanks and jump ASAP than scope and jump.
The theory, and test results (in the post linked in this thread), matches my own experience. Also while I know it depends on where you go, and has a bit of luck involved, but when I did my Anaconda core trip with 32t fuel, I had to re-route manually to refuel on multiple occasions. Each of those adds a significant amount of time to the trip due to having to find a nearby star, and then fly there and then find the original path I was going to (or something close to it).
So I still think there's no reason at all to go with a smaller fuel tank, unless you REALLY want to max out your auto-routing jump range (since with large tanks you can manually hop longer if you let your fuel drop), and the only place you need that are in the extremely sparse populated locations, primarily the edges of the galaxy (top, bottom sides etc).
Taking a smaller fuel tank, yet running with a 5D shield in an Anaconda - use a normal fuel tank and a 4D shield instead and get the same jump capability. You don't need stong shields to land safely (although practice landing sufficiently to know how to do it withotu damage before heading out). Alternatively if you're hellbent on a smaller tank, use 4D shields + smaller tank to get even better jump range.
