I never got friendly with the Orca, but the Beluga and Dolphin are awesome. They are great explorers if you don't focus on minmaxing your explorer for jump range. Mine both jump in the 50s - the Dolphin does just shy of 60 depending on outfitting, the Beluga does 55, I think.
The Beluga is your typical "bring all toys" luxury explorer. I don't remember how it's outfitted right now, but it allowed me to bring every fun tool I wanted, including a fighter bay. Downside is it runs hot, so mine needed some engineering (low emissions plant) to travel and scoop comfortably, and because of that it is a bit power starved and needs some good power management and priorities. But flying it is amazing. In supercruise it's the most agile of all the large ships, I think, and the view out of the canopy is just spectacular in VR. Also, you're doing your exploration in style.
The Dolphin is the coolest ship. Literally. It can scoop while charging the FSD, and I do that with a G5 OC plant. It makes it the fastest traveler, that's why it was so popular as bubble taxi before people used carriers for that. For exobiology, it can land on a stamp, it is fast, agile, but still tough enough - my Dolphin almost permaboosts to 530+, it has a total range of 350 ly or so before the tank is dry, all while having like 550 raw shields and 850 raw armor. Also it makes brilliant noises. I think the Dolphin also has the largest cargo capacity of the smalls if you disregard the Cobra IV.
Dolphin is the king of exploration and travel.
This is mine.